Ue and communication method for same

ABSTRACT

A User Equipment (UE) includes a transmitter configured to, in a case that, at a time when a Public Land Mobile Network (PLMN) is changed, a first timer is deactivated for a certain Data Network Name (DNN) and an old PLMN but a second timer is not running for the DNN or a new PLMN and is not deactivated, be capable of transmitting a PDU session establishment request message for the DNN or no DNN in the new PLMN without stopping the first timer. Thus, a communication control method is provided that is used in a case that, in 5G congestion control in which multiple types of congestion control are applied, the PLMN is changed during application of the congestion control.

TECHNICAL FIELD

The present application relates to a UE and a communication method forthe UE. This application claims priority based on JP 2018-117940 filedon Jun. 21, 2018 in Japan, the contents of which are incorporated hereinin its entirety by reference.

BACKGROUND ART

The 3rd Generation Partnership Project (3GPP), which undertakesactivities for standardizing recent mobile communication systems, hasstudied System Architecture Evolution (SAE) which is a systemarchitecture of Long Term Evolution (LTE). The 3GPP is in the process ofstandardizing Evolved Packet System (EPS) as a communication system forrealizing an all-Internet Protocol (IP) architecture. Note that a corenetwork constituting the EPS is called an Evolved Packet Core (EPC).

Additionally, the 3GPP recently has been studying a next-generationcommunication technology and a system architecture for 5th Generation(5G) mobile communication system which is a next-generation mobilecommunication system, Especially, as a system for achieving the 5Gmobile communication system, the 3GPP is in a process of standardizing5G System (5GS) (see NPL 1 and NPL 2). In the 5GS, technical problemsattributable to connection of various terminals to a cellular networkare extracted to standardize solutions.

For example, requirement conditions include optimization anddiversification of a communication procedure for supporting a continualmobile communication service depending on a terminal supporting variousaccess networks, optimization of a system architecture suitable for theoptimization and diversification of the communication procedure, and thelike.

CITATION LIST Non Patent Literature

NPL 1: 3GPP TS 23.501 v15.0.0; 3rd Generation Partnership Project;Technical Specification Group Services and System Aspects; SystemArchitecture for the 5G system; Stage 2 (Release 15)

NPL 2: 3GPP TS 23.502 v15.0.0; 3rd Generation Partnership Project;Technical Specification Group Services and System Aspects; Proceduresfor the 5G System; Stage 2 (Release 15)

SUMMARY OF INVENTION Technical Problem

For the 5GS, in addition to a mechanism providing a functioncorresponding to congestion control in an EPS, congestion control inNetwork Slices has further been studied (see NPL 1 and NPL 2).

However, in a rejection response to a terminal-initiated sessionmanagement request made while congestion control corresponding tocongestion control in the EPS and congestion control directed to networkslices are simultaneously in effect, processing has not been clarifiedthat is related to how the network indicates the congestion control ineffect to the terminal apparatus and how the terminal apparatus, havingreceived the rejection response, identifies the application of thecongestion control expected by the network. Additionally, processing hasnot been clarified that is performed in a case that a network-initiatedsession management request is received while the terminal apparatus iskeeping timers for congestion control associated with multiple types ofcongestion control active, the processing involving identifying thetimer for the congestion control to which the session management requestis directed. In addition, processing has not been clarified that isperformed in a case that the Public Land Mobile Network (PLMN) ischanged while the identified congestion control is in effect, theprocessing being related to the application of the congestion control inthe resultant PLMN.

In light of the foregoing, an object of the present invention is toprovide a mechanism and a communication control method for implementingmanagement processing such as congestion control for each network slice.

Solution to Problem

A User Equipment (UE, a terminal apparatus) according to an embodimentof the present invention includes a transmitter configured to, in a casethat, at a time when a Public Land Mobile Network (PLMN) is changed, afirst timer is deactivated for a certain Data Network Name (DNN) and anold PLMN but a second timer is not running for the DNN or a new PLMN andis not deactivated, be capable of transmitting a PDU sessionestablishment request message for the DNN or no DNN in the new PLMNwithout stopping the first timer.

The first timer and the second timer are timers for DNN-based congestioncontrol.

A communication method performed by a User Equipment (UE) according toone embodiment of the present invention includes the step of, in a casethat, at a time when a Public Land Mobile Network (PLMN) is changed, afirst timer is deactivated for a certain Data Network Name (DNN) and anold PLMN but a second timer is not running for the DNN or a new PLMN andis not deactivated, transmitting a PDU session establishment requestmessage for the DNN or no DNN in the new PLMN without stopping the firsttimer.

The first timer and the second timer are timers for DNN-based congestioncontrol and performed by the UE according to a third aspect,

Advantageous Effects of Invention

According to the present invention, the terminal apparatus constitutinga SGS and the apparatus in the core network can perform terminalapparatus-initiated or network-initiated management processing such ascongestion control for each network slice and/or for each DNN or APN.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem.

FIG. 2 is a diagram illustrating an example of a configuration and thelike of access networks in the mobile communication system.

FIG. 3 is a diagram illustrating an example of a configuration and thelike of a core network_A in the mobile communication system.

FIG. 4 is a diagram illustrating an example of a configuration and thelike of a core network_B in the mobile communication system.

FIG. 5 is a diagram illustrating an apparatus configuration of UE.

FIG. 6 is a diagram illustrating an apparatus configuration of an eNB/NRnode.

FIG. 7 is a diagram illustrating an apparatus configuration of anMME/AMF.

FIG. 8 is a diagram illustrating an apparatus configuration of anSMF/PGW/UPF.

FIG. 9 is a diagram illustrating an initial procedure.

FIG. 10 is a diagram illustrating a registration procedure.

FIG. 11 is a diagram illustrating a PDU session establishment procedure.

FIG. 12 is a diagram illustrating a network-initiated session managementprocedure.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment for carrying out the present invention will bedescribed below with reference to the drawings. Note that, as anexample, an embodiment of a mobile communication system to which thepresent invention is applied will be described in the presentembodiment.

1. SYSTEM OVERVIEW

An overview of a mobile communication system according to the presentembodiment will be described with reference to FIG. 1, FIG. 2, FIG. 3,and FIG. 4. FIG. 2 is a diagram for detailing access networks of themobile communication system of FIG. 1. FIG. 3 is a diagram mainlyillustrating details of a core network_A 90 in the mobile communicationsystem of FIG. 1. FIG. 4 is a diagram mainly illustrating details of acore network_B 190 in the mobile communication system of FIG. 1. Asillustrated in FIG. 1, the mobile communication system 1 according tothe present embodiment includes a terminal apparatus (which is alsoreferred to as a user apparatus or a mobile terminal apparatus) or aUser Equipment (UE)_A 10, an Access Network (AN)_A, an access network_B,and a Core Network (CN)_A 90, a core network_B 190, a Packet DataNetwork (PDN)_A 6, and a Data Network (DN)_A 5. Note that a combinationof the access network_A and the core network_A 90 may be referred to asan Evolved Packet System (EPS; 4G mobile communication system) or that acombination of the access network_B, the core network_B 190, and theUE_A 10 may be referred to as a 5G System (5GS; 5G mobile communicationsystem) or that configurations of the 5GS and EPS may not be limited tothese combinations. Note that, for the sake of simplicity, the corenetwork_A 90, the core network_B, or a combination thereof may also bereferred to as a core network, and the access network_A, the accessnetwork_B, or a combination thereof may also be referred to as an accessnetwork or a radio access network, and the DN_A 5, the PDN_A 6, or acombination thereof may also be referred to as a DN.

Here, the UE_A 10 may be an apparatus that can connect to a networkservice via 3GPP access (also referred to as 3GPP access or a 3GPPaccess network) and/or non-3GPP access (also referred to as non-3GPPaccess or a non-3GPP access network). In addition, the UE_A 10 may alsoinclude a Universal Integrated Circuit Card (UICC) and an embedded UICC(eUICC). Furthermore, the UE_A 10 may be a wirelessly connectableterminal apparatus and may be Mobile Equipment (ME), a Mobile Station(MS), a cellular Internet of Things (CIoT) terminal (CIoT UE), or thelike.

In addition, the UE_A 10 can be connected to an access network and/orcore network. In addition, the UE_A 10 can be connected to the DN_Aand/or the PDN_A via the access network and/or the core network. TheUE_A 10 transmits and/or receives (communicates) the user data to and/orfrom the DN_A and/or the PDN_A by using a Protocol Data Unit or PacketData Unit (PDU) session and/or a Packet Data Network (PDN) connection(also referred to as PDN connection). Furthermore, the communication ofthe user data is not limited to Internet Protocol (IP) communication(IPv4 or IPv6), and may be, for example, non-IP communication in theEPS, or Ethernet (registered trademark) communication or Unstructuredcommunication at the 5GS.

Here, IP communication is data communication using IP, and is datacommunication achieved by transmitting and/or receiving an IP packetincluding an IP header. Note that a payload section constituting the IPpacket may include the user data transmitted and/or received by the UE_A10. Furthermore, non-IP communication is data communication withoutusing IP, and is data communication achieved by transmitting and/orreceiving data without IP header. For example, the non-IP communicationmay be the data communication achieved through transmitting and/orreceiving application data not given the IP address, or may transmitand/or receive the user data transmitted and/or received by the UE_A 10to which another header such as a MAC header and an Ethernet (registeredtrademark) frame header is given.

Additionally, the PDU session is connectivity established between theUE_A 10 and the DN_A 5 to provide a PDU connection service. To be morespecific, the PDU session may be connectivity established between theUE_A 10 and an external gateway, Here, the external gateway may be aUPF, a Packet Data Network Gateway (PGW), or the like. Additionally, thePDU session may be a communication path established to transmit and/orreceive the user data between the UE_A 10 and the core network and/orthe DN, or a communication path established to transmit and/or receivethe PDU. Furthermore, the PDU session may be a session establishedbetween the UE_A 10 and the core network and/or the DN, or may be alogical communication path including a transfer path such as one or morebearers and the like between apparatuses in the mobile communicationsystem 1. To be more specific, the PDU session may be a connectionestablished by the UE_A 10 between a core network_B 190 and/or theexternal gateway, or may be a connection established between the UE_A 10and a UPF. Additionally, the PDU session may be connectivity and/or aconnection between the UE_A 10 and the UPF_A 235 via an NR node_A 122.Furthermore, the PDU session may be identified by a PDU session IDand/or an EPS bearer ID.

Note that the UE_A 10 can transmit and/or receive the user data toand/or from an apparatus, such as an application server, that is locatedin the DN_A 5 by using the PDU session. In other words, the PDU sessioncan transfer the user data transmitted and/or received between the UE_A10 and the apparatus, such as the application server, that is located inthe DN_A 5. Furthermore, each apparatus (the UE_A 10, the apparatus inthe access network, and/or the apparatus in the core network, and/or theapparatus in the data network) may correlate one or more pieces ofidentification information to the PDU session for management. Note thatthese pieces of identification information may include at least one ofan Access Point Name (APN), a Traffic Flow Template (TFT), a sessiontype, application identification information, identification informationof the DN_A 5, Network Slice instance (NSI) identification information,Dedicated Core Network (DCN) identification information, and accessnetwork identification information, or may further include otherinformation. Furthermore, in a case that multiple PDU sessions areestablished, respective pieces of identification information correlatedto the PDU sessions may be the same contents or may be differentcontents. Furthermore, the NSI identification information is informationfor identifying an NSI, and hereinafter may be an NSI ID or a SliceInstance ID.

In addition, the access network_A and/or the access network_B may be anyof a Universal Terrestrial Radio Access Network (UTRAN)_A 20, an EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN)_A 80, and NG-RAN(5G-RAN)_A 120 as illustrated in FIG. 2. Note that hereinafter, theUTRAN_A 20 and/or E-UTRAN_A 80 and/or the NG-RAN_A 120 may be referredto as a 3GPP access or a 3GPP access network, and the wireless LANaccess network or non-3GPP AN may be referred to as a non-3GPP access ora non-3GPP access network. Each radio access network includes anapparatus to which the UE_A 10 is actually connected (e.g., a basestation apparatus or an access point), and the like.

For example, the E-UTRAN_A 80 is an access network for Long TermEvolution (LTE) and configured to include one or more eNBs_A 45. TheeNB_A 45 is a radio base station to which the UE_A 10 connects throughEvolved Universal Terrestrial Radio Access (E-UTRA). Furthermore, in acase that multiple eNBs are present in the E-UTRAN_A 80, the multipleeNBs may be connected to each other.

Additionally, the NG-RAN_A 120 is a 5G access network, may be an (R) ANdescribed in FIG. 4, and includes one or more New Radio AccessTechnology nodes (NR nodes)_A 122 and/or ng-eNBs. The NR node_A 122 is aradio base station to which the UE_A 10 connects with 5G Radio Accessand is also referred to as a gNB. Note that the ng-eNB may be an eNB(E-UTRA) configuring a 5G access network, may be connected to the corenetwork_B 190 via the NR node_A, or may be directly connected to thecore network_B 190. Additionally, in a case that there are multiple NRnodes_A 122 and/or ng-eNB in the NG-RAN_A 120, the NR nodes_A 122 and/orng-eNBs may be connected to one another.

Note that the NG-RAN_A 120 may be an access network including the E-UTRAand/or the 5G Radio Access. In other words, the NG-RAN_A 120 may includethe eNB_A 45, the NR node_A 122, or both the eNB_A 45 and the NR node_A122. In this case, the eNB_A 45 and the NR node_A 122 may be similarapparatuses. Therefore, the NR node_A 122 can be substituted with theeNB_A 45.

The UTRAN_A 20 is an access network in a 3G mobile communication system,and includes a Radio Network Controller (RNC)_A 24 and a Node B (NB)_A22. The NB_A 22 is a radio base station to which the UE_A 10 connectsthrough Universal Terrestrial Radio Access (UTRA), and the UTRAN_A 20may include one or multiple radio base stations. Furthermore, the RNC_A24 is a controller for connecting the core network_A 90 and the NB_A 22,and the UTRAN_A 20 may be configured to include one or multiple RNCs.Moreover, the RNC_A 24 may be connected to one or multiple NBs_A 22.

Note that, in the present specification, the expression “the UE_A 10 isconnected to each radio access network” is equivalent to “the UE_A 10 isconnected to a base station apparatus, an access point, or the likeincluded in each radio access network,” and is equivalent to“transmitted and/or received data, signals, and the like are alsotransferred through the base station apparatus and the access point.”Note that control messages transmitted and/or received between the UE_A10 and the core network_B 190 may be the same control message,regardless of a type of the access network. Accordingly, the expression“UE_A 10 and the core network_B 190 transmit and/or receive a message toand/or from each other via the NR node_A 122” may be equivalent to theexpression “UE_A 10 and the core network_B 190 transmit a message toeach other via the eNB_A 45.”

Furthermore, the access network is a radio network connecting with theUE_A 10 and/or the core network. The access network may be a 3GPP accessnetwork, or a non-3GPP access network. Note that the 3GPP access networkmay be the UTRAN_A 20, the E-UTRAN_A 80 and the NG-Radio Access Network(RAN)_A 120, and the non-3GPP access network may be a wireless LANaccess point (WLAN AN). Note that the UE_A 10 may connect to the accessnetwork or to the core network via the access network in order toconnect to the core network.

Additionally, the DN_A 5 and the PDN_A 6 are Data Networks that providecommunication services to the UE_A 10, may be configured as packet dataservice networks, and may be configured for each service. Furthermore,the DN_A 5 may include a connected communication terminal. Accordingly,connecting with the DN_A 5 may be connecting with the communicationterminal or a server device located in the DN_A 5. Furthermore, thetransmission and/or reception of the user data to and/or from the DN_A 5may be transmission and/or reception of the user data to and/or from thecommunication terminal or server device located in the DN_A 5. Inaddition, although the DN_A 5 is outside the core networks in FIG. 1,DN_A 5 may be within the core networks.

Additionally, the core network_A 90 and/or the core network_B 190 may beconfigured as one or more apparatuses in the core network. Here, theapparatuses in the core network apparatuses may be apparatuses thatperform part or all of processing or functions of apparatuses includedin the core network_A 90 and/or the core network_B 190. Note that theapparatus in the core network may be referred to as a core networkapparatus.

Furthermore, the core network is an IP mobile communication network,operated by a Mobile Network Operator (MNO), that connects to the accessnetwork and/or the DN. The core network may be a core network for amobile communication operator that operates and manages the mobilecommunication system 1, or may be a core network for a virtual mobilecommunication operator such as a Mobile Virtual Network Operator (MVNO)and a Mobile Virtual Network Enabler (MVNE), or a virtual mobilecommunication service provider. Note that the core network_A 90 may bean Evolved Packet Core (EPC) constituting an Evolved Packet System(EPS), and the core network_B 190 may be a 5G Core Network (5GC)constituting a 5GS. Furthermore, the core network_B 190 may be a corenetwork for a system providing the 5G communication service. Conversely,the EPC may be the core network_A 90, and the 5GC may be the corenetwork_B 190. Note that the core network_A 90 and/or the core network_B190 is not limited to the above, and may be a network for providing amobile communication service.

Now, the core networks_A 90 will be described. The core network_A 90 mayinclude at least one of a Home Subscriber Server (HSS)_A 50, anAuthentication Authorization Accounting (AAA), a Policy and ChargingRules Function (PCRF), the PGW_A 30, an ePDG, the SGW_A 35, the MobilityManagement Entity (MME)_A 40, a Serving GPRS Support Node (SGSN), and anSCEF. Furthermore, these may also be configured as Network Functions(NFs). The NF may be a processing function included in a network. Inaddition, the core network_A 90 is capable of connecting to multipleradio access networks (the UTRAN_A 20 and the E-UTRAN_A 80).

Although only the HSS (HSS_A 50), the PGW (PGW_A 30), the SGW (SGW_A35), and the MME (MME_A 40) among the network elements are described inFIG. 3 for simplicity, it does not mean that no other apparatuses and/orNFs are included therein. Note that the UE_A 10 is also referred to as aUE, the HSS_A 50 as an HSS, the PGW_A 30 as a PGW, the SGW_A 35 as anSGW, the MME_A 40 as an MME, and the DN_A 5 and/or the PDN_A 6 as a DNor a PDN for simplicity.

The following briefly describes each apparatus included in the core netnetwork_A 90.

The PGW_A 30 is a relay apparatus that is connected to the DN, the SGW_A35, the ePDG, the WLAN ANa 70, the PCRF, and the AAA, and transfers theuser data as a gateway between the DN (the DN_A 5 and/or the PDN_A 6)and the core network_A 90. Note that the PGW_A 30 may serve as a gatewayfor the IP communication and/or non-IP communication. Furthermore, thePGW_A 30 may have a function to transfer the IP communication, or mayhave a function to perform conversion between the non-IP communicationand the IP communication. Note that multiple gateways like this may bedeployed in the core network_A 90. Furthermore, the multiple gatewaysdeployed may serve as gateways for connecting the core network_A 90 witha single DN.

Note that a User Plane (U-Plane or UP) may be a communication path fortransmitting and/or receiving user data, and may include multiplebearers. Furthermore, a Control Plane (C-Plane or CP) may be acommunication path for transmitting and/or receiving a control message,and may include multiple bearers.

Furthermore, the PGW_A 30 may be connected to the SGW and the DN and aUser plane function (UPF) and/or a Session Management Function (SMF) ormay be connected to the UE_A 10 via the U-Plane. Furthermore, the PGW_A30 may be configured integrally with the UPF_A 235 and/or the SMF_A 230.

The SGW_A 35 is a relay apparatus that is connected to the PGW_A 30, theMME_A 40, the E-UTRAN_A 80, the SGSN, and the UTRAN_A 20, and transfersthe user data as a gateway between the core network_A 90 and the 3GPPaccess networks (the UTRAN_A 20, the GERAN, and the E-UTRAN_A 80).

The MME_A 40 is a control apparatus that is connected to the SGW_A 35,the access network, the MSS_A 50, and the SCEF, and performs locationinformation management including mobility management of the UE_A 10 viathe access network, and access control. Furthermore, the MME_A 40 mayinclude a function as a session management device to manage a sessionestablished by the UE_A 10. Multiple control apparatuses like this maybe deployed in the core network_A 90, and, for example, a locationmanagement apparatus different from the MME_A 40 may be configured. Likethe MME_A 40, the location management apparatus different from the MME_A40 may be connected to the SGW_A 35, the access network, the SCEF, andthe HSS_A 50. Furthermore, the MME_A 40 may be connected to an Accessand Mobility Management Function (AMF).

Furthermore, in a case that multiple MMEs are included in the corenetwork_A 90, the multiple MMEs may be connected to each other. Withthis configuration, a context of the UE_A 10 may be transmitted and/orreceived between the MMEs. In this way, the MME_A 40 is a managementapparatus to transmit and/or receive the control information related tothe mobility management and the session management to and/or from theUE_A 10. In other words, the MME_A 40 may be a control apparatus for aControl Plane (C-Plane; CP).

The example is described in which the MME_A 40 is configured to beincluded in the core network_A 90, but the MME_A 40 may be a managementapparatus configured in one or multiple core networks, DCNs, or NSIs, ormay be a management apparatus connected to one or multiple corenetworks, DCNs, or NSIs. Here, multiple DCNs or NSIs may be operated bya single network operator, or by different network operatorsrespectively.

The MME_A 40 may be a relay apparatus for transferring the user data asa gateway between the core network_A 90 and the access network. Notethat the user data transmitted and/or received by the MME_A 40 servingas a gateway may be small data.

Furthermore, the MME_A 40 may be an NF having a function of the mobilitymanagement of the UE_A 10 or the like, or an NF managing one or multipleNSIs. The MME_A 40 may be an NF having one or multiple of thesefunctions. Note that the NF may be one or multiple apparatuses deployedin the core network_A 90, a CP function (hereinafter, also referred toas a Control Plane Function (CPF) or a Control Plane Network Function)for the control information and/or control message, or a common CPfunction shared between multiple network slices.

Here, the NF is a processing function included in a network. That is,the NF may be a function apparatus such as an MME, an SGW, a PGW, a CPF,an AMF, an SMF, or a UPF, or may be a function such as mobilitymanagement (MM) and session management (SM), or capability information.The NF may be a function device to realize a single function, or afunction device to realize multiple functions. For example, an NF torealize the MM function and an NF to realize the SM function may beseparately present, or an NF to realize both the MM function and the SMfunction may be present.

The HSS_A 50 is a managing node that is connected to the MME_A 40, theAAA, and the SCEF, and manages subscriber information. The subscriberinformation of the HSS_A 50 is referred to during the access controlperformed by the MME_A 40, for example. Furthermore, the HSS_A 50 may beconnected to a location management device different from the MME_A 40.For example, the HSS_A 50 may be connected to the CPF_A 140.

Furthermore, the HSS_A 50, a Unified Data Management (UDM_A 245 may beconfigured as different apparatuses and/or NFs or the same apparatusand/or NF.

The AAA is connected to the PGW 30, the HSSA 50, the PCRF, and the WLANANa 70 and performs access control for the UE_A 10 connected via theWLAN ANa 70.

The PCRF is connected to the PGW_A 30, the WLAN ANa 75, the AAA, theDN_A 5 and/or the PDN_A 6 and performs QoS management on data delivery.For example, the PCRF manages QoS of a communication path between theUE_A 10, the DN_A 5, and/or the PDN_A 6. Furthermore, the PCRF may be anapparatus to create and/or manage a Policy and Charging Control (PCC)rule and/or a routing rule used by each apparatus for transmittingand/or receiving user data.

In addition, the PCRF may be a PCF to create and/or manage a policy.More specifically, the PCRF may be connected to the UPF_A 235.

The ePDG is connected to the PGW 30 and the WLAN ANb 75 and deliversuser data as a gateway between the core network_A 90 and the WLAN ANb75.

The SGSN is a control apparatus, connected to the UTRAN_A 20, the GERAN,and the SGW_A 35, for performing location management between the accessnetwork (UTRAN/GERAN) of 3G/2G and the access network (E-UTRAN) of LTE(4G). In addition, the SGSN has functions of selecting the PGW and theSGW, managing a time zone of the UE_A 10, and selecting the MME_A 40 atthe time of handover to the E-UTRAN.

The SCEF is a relay apparatus that is connected to the DN_A 5 and/or thePDN_A 6, the MME_A 40, and the HSS_A 50 and transfers the user data as agateway for connecting the DN_A 5 and/or the PDN_A 6 with the corenetwork_A 90. Note that the SCEF may serve as a gateway for non-IPcommunication. Furthermore, the SCEF may have a function to performconversion between non-IP communication and IP communication. Multiplegateways like this may be deployed in the core network_A 90.Furthermore, multiple gateways connecting the core network_A 90 with asingle DN_5 and/or PDN_A 6 and/or DN may be also deployed. Note that theSCEF may be outside or inside the core network.

Next, the core network_B 190 will be described, Next, the core network_B190 may include at least one of an Authentication Server Function(AUSF), an Access and Mobility Management Function (AMF)_A 240, anUnstructured Data Storage Function (UDSF), a Network Exposure Function(NEF), an Network Repository Function (NRF), a Policy Control Function(PCF), a Session Management Function (SMF)_A 230, a Unified DataManagement (UDM), a User Plane Function (UPF)_A 235, an ApplicationFunction (AF), and a Non-3GPP InterWorking Function (N3IWF).Furthermore, these may also be configured as Network Functions (NFs).The NF may be a processing function included in a network.

Although, among the above-described elements, only the AMF (AMF_A 240),the SMF (SMF_A 230), and the UPF (UPF_A 235) are illustrated in FIG. 4for simplicity, it does not mean that no other elements (apparatusesand/or Network Functions (NFs)) are included. Note that the UE_A 10 willalso be referred to as a UF, the AMF_A 240 as an AMF, the SMF_A 230 asan SMF, the UPF_A 235 as a UPF, and the DN_A 5 as a DN for simplicity.

In addition, FIG. 4 illustrates an N1 interface (hereinafter, alsoreferred to as a reference point), an N2 interface, an N3 interface, anN4 interface, an N6 interface, an N9 interface, and an N11 interface.Here, the N1 interface is an interface between the UE and the AMF, theN2 interface is an interface between (R) access network (AN) and theAMF, and the N3 interface is an interface between the (R) access network(AN) and the UPF, the N4 interface is an interface between the SMF andthe UPF, the N6 interface is an interface between the UPF and the DN,the N9 interface is an interface between the UPF and the UPF, and theN11 interface is an interface between the AMF and the SMF. Theseinterfaces can be used to perform communication between the apparatuses.Here, the (R) AN is hereinafter also referred to as the NG RAN.

The following briefly describes each apparatus included in the corenetwork_B 190.

First, the AMF_A 240 is connected to another AMF, the SMF (SMF_A 230),the access network (i.e., the UTRAN_A 20, the E-UTRAN_A 80, and theNG-RAN_A 120), the UDM, the AUSF, and the PCF. The AMF_A 240 may playroles of registration management, connection management, reachabilitymanagement, mobility management of the UE_A 10 or the like, transfer ofa Session Management (SM) message between the UE and the SMF, accessauthentication or access authorization, a Security Anchor Function(SEA), Security Context Management (SCM), support for the N2 interfacefor the N3IWF, support for transmission and/or reception of NAS signalsto and/or from the UE via the N3IWF, authentication of the UE connectedvia the N3IWF, management of Registration Management (RM) states,management of Connection Management (CM) states, and the like. Inaddition, one or more AMF_A 240s may be deployed within the corenetwork_B 190. In addition, the AMF_A 240 may be an NF that manages oneor more Network Slice Instances (NSI). In addition, the AMF_A 240 mayalso be a Common Control Plane Network Function (Common CPNF, or CCNF)shared among multiple NSIs.

Additionally, the RM state includes a deregistered state(RM-DEREGISTERED state) and a registered state (RM-REGISTERED state). Inthe RM-DEREGISTERED state, the UE is not registered in the network, andthus the AMF is not able to reach the UE because the UE context in theAMF does not have valid location information and routing information forthe UE. In the RM-REGISTERED state, the UE is registered in the network,and thus the UE can receive services that requires registration with thenetwork.

Additionally, the CM state includes a disconnected state (CM-IDLE state)and a connected state (CM-CONNECTED state). In the CM-IDLE state, the UEis in the RM-REGISTERED state but does not have a NAS signalingconnection established between the AMF and the UE via the N1 interface.Also, in the CM-IDLE state, the UE does not have an N2 interfaceconnection (N2 connection) and an N3 interface connection (N3connection). On the other hand, in the CM-CONNECTED state, the UE hasthe NAS signaling connection established between the AMF and the UE viathe N1 interface. Also, in the CM-CONNECTED state, the UE may have theN2 interface connection (N2 connection) and/or the N3 interfaceconnection (N3 connection).

Additionally, the SMF_A 230 may have a Session Management (SM) functionsuch as a PDU session, or the like, IP address allocation for the UE anda management function for the IP address allocation, a UPF selection andcontrol function, a UPF configuration function for routing traffic to anappropriate destination, a function for notifying arrival of downlinkdata (Downlink Data Notification), a function for providing AN-unique SMinformation (for each AN) transmitted, via an N2 interface, to the ANvia the AMF, a function for determining a Session and Service Continuitymode (SSC mode) for a session, a roaming function, and the like.Additionally, the SMF_A 230 may be connected to the AMF_A 240, the UPF_A235, the UDM, and the PCF.

In addition, the UPF_A 235 is connected to the DN_A 5, the SMF_A 230,another UPF, and the access network (i.e., the UTRAN_A 20, the E-UTRAN_A80, and the NG-RAN_A 120). The UPF_A 235 may play roles of an anchor tointra-RAT mobility or inter-RAT mobility, packet routing & forwarding,an uplink classifier (UL CL) function to support routing of multipletraffic flows for one DN, a branching point function to support amulti-homed PDU session, QoS processing for a user plane, verificationof uplink traffic, buffering of downlink packets, a function oftriggering downlink data notification, and the like. Furthermore, theUPF_A 235 may be a relay apparatus that transfers the user data as agateway between the DN_A 5 and the core network_B 190. Note that theUPF_A 235 may serve as a gateway for IP communication and/or non-IPcommunication. Furthermore, the UPF_A 235 may have a function oftransferring IP communication or a function to perform conversionbetween non-IP communication and IP communication. The multiple gatewaysdeployed may serve as gateways for connecting the core network_B 190with a single DN. Note that the UPF_A 235 may have connectivity withanother NF or may be connected to each apparatus via another NF.

A UPF_C 239 (also referred to as a branching point or an uplinkclassifier), which is a UPF different from the UPF_A 235, may be presentbetween the UPF_A 235 and the access network as an apparatus or an NF.In a case that the UPF_C 239 is present, the PDU session between theUE_A 10 and the DN_A 5 is established via the access network, the UPF_C239, and the UPF_A 235.

Additionally, the AUSF is connected to the UDM and the AMF_A 240. TheAUSF functions as an authentication server.

The UDSF provides a function for all NFs to store or retrieveinformation as unstructured data.

The NEF provides a means to securely provide services and capabilitiesprovided by the 3GPP network. The NEF stores information received fromanother NF as structured data.

In a case that a NF discovery request is received from a NF instance,the NRF provides the NF with information of found NF instances or holdsinformation of available NF instances or services supported by theinstances.

The PCF is connected to the SMF (SMF_A 230), the AF, and the AMF_A 240.The PCF provides a policy rule and the like.

The UDM is connected to the AMF_A 240, the SMF (SMF_A 230), the AUSF,and the PCF. The UDM includes a UDM FE (application front end) and aUser Data Repository (UDR). The UDM FE performs processing ofauthentication information (credentials), location management,subscriber management (subscription management), and the like. The UDRstores data necessary for the UDM FE for provision and the policyprofile necessary for the PCF.

The AF is connected to the PCF. The AF affects traffic routing or isinvolved in the policy control.

The N3IWF provides functions of establishing an IPsec tunnel with theUE, relaying NAS (N1) signaling between the UE and the AMF, processingN2 signaling transmitted from the SMF and relayed by the AMF,establishing IPsec Security Association (IPsec SA), relaying user planepackets between the UE and the UPF, selecting the AMF, and the like.

1.2. Configuration of Each Apparatus

The configuration of each apparatus will be described below. Note thatsome or all of apparatuses to be described below and functions of unitsof the apparatuses may operate on physical hardware, or logical hardwarewhich is virtually configured on general-purpose hardware.

1.2.1. Configuration of UE

First, an example of an apparatus configuration of the UE_A 10 isillustrated in FIG. 5. As illustrated in FIG. 5, the UE_A 10 includes acontroller_A 500, a transmission and/or reception unit_A 520, and astorage unit_A 540. The transmission and/or reception unit_A 520 and thestorage unit_A 540 are connected to the controller_A 500 via a bus.Furthermore, an external antenna 410 is connected to the transmissionand/or reception unit_A 520.

The controller_A 500 is a function unit for controlling the entire UE_A10 and implements various processes of the entire UE_A 10 by reading outand performing various types of information and programs stored in thestorage unit_A 540.

The transmission and/or reception unit_A 520 is a function unit throughwhich the UE_A 10 connects to the base station (the UTRAN_A 20 and the.E-UTRAN_A 80 and the NG-RAN_A 120) and/or the wireless LAN access point(the WLAN AN) in the access network to connect to the access network. Inother words, the UE_A 10 can connect to the base station and/or theaccess point in the access network via the external antenna 410connected to the transmission and/or reception unit_A 520. To bespecific, the UE_A 10 can transmit and/or receive user data and/orcontrol information to and/or from the base station and/or the accesspoint in the access network via the external antenna 410 connected tothe transmission and/or reception unit_A 520.

The storage unit_A 540 is a function unit that stores programs, data,and the like necessary for each operation of the UE_A 10, and include,for example, a semiconductor memory, a Hard Disk Drive (HDD), a SolidState Drive (SSD), or the like. The storage unit_A 540 storesidentification information, control information, a flag, a parameter, arule, a policy, and the like included in a control message which istransmitted and/or received in the communication procedure describedbelow.

1.2.2 eNB/NR Node

Now, FIG. 6 illustrates an example of an apparatus configuration of theeNB_A 45 and the NR node_A 122. As illustrated in FIG. 6, the eNB_A 45and the NR node_A 122 include a controller_B 600, a network connectionunit_B 620, a transmission and/or reception unit_B 630, and a storageunit_B 640. The network connection unit_B 620, the transmission and/orreception unit_B 630, and the storage unit_B 640 are connected to thecontroller_B 600 via a bus. Additionally, an external antenna 510 isconnected to the transmission and/or reception unit_B 630.

The controller_B 600 is a function unit for controlling the entire eNB_A45 and NR node_A 122, and implements various processes of the entireeNB_A 45 and NR node_A 122 by reading out and performing various typesof information and programs stored in the storage unit_B 640.

The network connection unit_B 620 is a function unit through which theeNB_A 45 and the NR node_A 122 connect to the AMF_A 240 and the UPF_A235 in the core network. In other words, the eNB_A 45 and the NR node_A122 can be connected to the AMF_A 240 and the UPF_A 235 in the corenetwork via the network connection unit_B 620. Specifically, the eNB_A45 and the NR node_A 122 can transmit and/or receive user data and/orcontrol information to and/or from the AMF_A 240 and/or the UPF_A 235via the network connection unit_B 620.

The transmission and/or reception unit_B 630 is a function unit throughwhich the eNB_A 45 and the NR node_A 122 connect to the UE_A 10. Inother words, the eNB_A 45 and the NR node_A 122 can transmit and/orreceive user data and/or control information to and/or from the UE_A 10via the transmission and/or reception unit_B 630.

The storage unit_B 640 is a function unit for storing programs, data,and the like necessary for each operation of the eNB_A 45 and the NRnode_A 122. The storage unit_B 640 includes, for example, asemiconductor memory, an HDD, an SSD, or the like. The storage unit_B640 stores identification information, control information, a flag, aparameter, and the like included in a control message which istransmitted and/or received in the communication procedure describedbelow. The storage unit_B 640 may store these pieces of information asthe contexts for each UE_A 10.

1.2.3. Configuration of MME/AMF

Now, FIG. 7 illustrates an example of an apparatus configuration of theMME_A 40 or the AMF_A 240. As illustrated in FIG. 7, the MME_A 40 or theAMF_A 240 includes a controller_C 700, a network connection unit_C 720,and a storage unit_C 740. The network connection unit_C 720 and thestorage unit_C 740 are connected to the controller_C 700 via a bus.Furthermore, the storage unit_C 740 stores a context 642.

The controller_C 700 is a function unit for controlling the entire MME_A40 or AMF_A 240. The controller_C 600 reads out and performs variouskinds of information and programs stored in the storage unit_C 740 toachieve various processes of the entire AMF_A 240.

The network connection unit_C 720 is a function unit through which theMME_A 40 or the AMF_A 240 connects to another MME_A 40, the AMF_240, theSMF_A 230, and a base station (the UTRAN_A 20 and the E-UTRAN_A 80 andthe NG-RAN_A 120) and/or the wireless LAN access point (the WLAN AN),the UDM, the AUSF, and the PCF in the access network. In other words,the MME_A 40 or the AMF_A 240 can transmit and/or receive user dataand/or control information to and/or from the base station and/or accesspoint, the UDM, the AUSF, and the PCF in the access network via thenetwork connection unit_C 720.

The storage unit_C 740 is a function unit for storing programs, data,and the like necessary for each operation of the MME_A 40 or the AMF_A240. The storage unit_C 740 includes, for example, a semiconductormemory, an HDD, an SSD, or the like. The storage unit_C 740 storesidentification information, control information, a flag, a parameter,and the like included in a control message which is transmitted and/orreceived in the communication procedure described below. Examples of thecontext 642 stored in the storage unit_C 740 may include a contextstored for each UE, a context stored for each PDU session, and a contextstored for each bearer. The context stored for each UE may include anIMSI, an MSISDN, MM State, a GUTI, a ME Identity, a UE radio accesscapability, a UE network capability, an MS network capability, an accessrestriction, an MME F-TEID, an SGW F-TEID, an eNB address, an MME UES1AP ID, an eNB UE S1AP ID, an NR node address, an NR node ID, a WAGaddress, and a WAG ID. Furthermore, the context stored for each PDUsession may include an APN in Use, an assigned session type, IPaddress(es), a PGW F-TEID, an SCEF ID, and a default bearer.Additionally, the context stored for each bearer may include an EPSbearer ID, a TI, a TFT, an SGW F-TEID, a PGW F-TEID, an MME F-TEID, aneNB address, an NR node address, a WAG address, an eNB ID, an NR nodeID, and a WAG ID.

1.2.4. Configuration of SMF

Next, FIG. 8 illustrates an example of an apparatus configuration of theSMF_A 230. As illustrated in FIG. 8, the SMF_A 230 includes acontroller_D 800, a network connection unit_D 820, and a storage unit_D840. The network connection unit_D 820 and the storage unit_D 840 areconnected to the controller_D 800 via a bus. In addition, the storageunit_D 840 stores a context 742.

The controller_D 800 of the SMF_A 230 is a function unit for controllingthe entire SMF_A 230 and implements various processes of the entireSMF_A 230 by reading out and performing various types of information andprograms stored in the storage unit_D 840.

Additionally, the network connection unit_D 820 in the SMF_A 230 is afunction unit for the SMF_A 230 to connect to the AMF_A 240, the UPF_A235, the UDM, and the PCF. In other words, the SMF_A 230 can transmitand/or receive user data and/or control information to and/or from theAMF_A 240, the UPF_A 235, the UDM, and the PCF via the networkconnection unit_D 820.

Additionally, the storage unit_D 840 of the SMF_A 230 is a function unitfor storing programs, data, and the like necessary for each operation ofthe SMF_A 230. The storage unit_D 840 of the SMF_A 230 includes, forexample, a semiconductor memory, an HDD, an SSD, or the like. Thestorage unit_D 840 of the SMF_A 230 stores identification information,control information, a flag, a parameter, and the like included in acontrol message which is transmitted and/or received in thecommunication procedure described below. In addition, examples of thecontext 742 stored in the storage unit_D 840 of the SMF_A 230 mayinclude a context stored for each UE, a context stored for each APN, acontext stored for each PDU session, and a context stored for eachbearer. The context stored for each UE may include an IMSI, an MEIdentity, an MSISDN, and a RAT type. The context stored for each APN mayinclude an APN in use. Note that the context stored for each APN may bestored for each data network identifier. The context stored for each PDUsession may include an assigned session type, IP address(es), an SGWF-TEID, a PGW F-TEID, and a default bearer. The context stored for eachbearer may include an EPS bearer ID, a TFT, an SGW F-TEID, and a PGWF-TEID.

1.2.5. Configuration of PGW/UPF

Next, FIG. 8 illustrates an example of an apparatus configuration of thePGW_A 30 or the UPF_A 235. As illustrated in FIG. 8, each of the PGW_A30 or the UPF_A 235 includes the controller_D 800, the networkconnection unit_D 820, and the storage unit_D 840. The networkconnection unit_D 820 and the storage unit_D 840 are connected to thecontroller_D 800 via a bus. In addition, the storage unit_D 840 stores acontext 742.

The controller_D 800 of the PGW_A 30 or the UPF_A 235 is a function unitfor controlling the entire PGW_A 30 or UPF_A 235, and implements varioussteps of processing of the entire PGW_A 30 or UPF_A 235 by reading outand performing various types of information and programs stored in thestorage unit_D 840.

The network connection unit_D 820 in the PGW_A 30 or the UPF_A 235 is afunction unit for the PGW_A 30 or the UPF_A 235 to connect to the DN(that is, the DN_A 5), the SMF_A 230, another UPF_A 235, and the accessnetwork (that is, the UTRAN_A 20 and the E-UTRAN_A 80 and the NG-RAN_A120). In other words, the UPF_A 235 can transmit and/or receive the userdata and/or the control information to and/or from the DN (that is, theDN_A 5), the SMF_A 230, another UPF_A 235, and the access network (thatis, the UTRAN_A 20 and the E-UTRAN_A 80 and the NG-RAN_A 120) via thenetwork connection unit_D 820.

Additionally, the storage unit_D 840 in the UPF_A 235 is a function unitfor storing programs, data, and the like necessary for each operation bythe UPF_A 235. The storage unit_D 840 in the UPF_A 235 includes, forexample, a semiconductor memory, an HDD, an SSD, or the like. Thestorage unit_D 840 in the UPF_A 235 stores identification information,control information, a flag, a parameter, and the like included in thecontrol message transmitted and/or received in a communication proceduredescribed below. In addition, examples of the context 742 stored in thestorage unit_D 840 of the UPF_A 235 may include a context stored foreach UE, a context stored for each APN, a context stored for each PDUsession, and a context stored for each bearer. The context stored foreach UE may include an IMSI, an ME identity, an MSISDN, and a RAT type.The context stored for each APN may include an APN in use. Note that thecontext stored for each APN may be stored for each data networkidentifier. The context stored for each PDU session may include anassigned session type, IP address (es), an SGW F-TEID, a PGW F-TEID, anda default bearer. The context stored for each bearer may include an EPSbearer ID, a TFT, an SGW F-TEID, and a PGW F-TEID.

1.2.6. Information Stored in Storage Unit of Each Apparatus

Next, each piece of information stored in the storage unit of each ofthe above-described apparatuses will be described.

An International Mobile Subscriber Identity (IMSI) is permanentidentification information of a subscriber (user), and is identificationinformation assigned to a user using the UE. The IMSI stored by the UE_A10, the MME_A 40/CPF_A 140/AMF_A 2400, and the SGW_A 35 may be the sameas the IMSI stored by an HSS_A 50.

The EMM State/MM State indicates a mobility management state of the UE_A10 or the MME_A 40/CPF_A 140/AMF_A 240. For example, the EMM State/MMState may be an EMM-REGISTERED state (registered state) in which theUE_A 10 is registered in the network, and/or an EMM-DEREGISTERD state(deregistered state) in which the UE_A 10 is not registered in thenetwork. The EMM State/MM State may be an ECM-CONNECTED state in which aconnection is maintained between the UE_A 10 and the core network,and/or an ECM-IDLE state in which the connection is released. Note thatthe EMM State/MM State may be information for distinguishing a state inwhich the UE_A 10 is registered in the EPC from a state in which theUE_A 10 is registered in the NGC or 5GC.

The Globally Unique Temporary Identity (GUTI) is temporaryidentification information of the UE_A 10. The GUTI includesidentification information (Globally Unique MME Identifier (GUMMEI)) ofthe MME_A 40/CPF_A 140/AMF_A 240 and identification information(M-Temporary Mobile Subscriber Identity (M-TMSI)) of the UE_A 10 in aspecific MME_A 40/CPF_A 140/AMF_A 240. The ME Identity is an ID of theUE_A 10 or the ME, and may be International Mobile Equipment Identity(IMEI) or IMEI Software Version (IMEISV), for example. The MSISDNrepresents a basic phone number of the UE_A 10. The MSISDN stored by theMME_A 40/CPF_A 140/AMF_A 240 may be information indicated by the storageunit of the HSS_A 50. Note that the GUTI may include information foridentifying the CPF_140.

The MME F-TEID is information for identifying the MME_A 40/CPF_A140/AMF_A 240. The MME F-TEID may include an IP address of the MME_A40/CPF_A 140/AMF_A 240, a Tunnel Endpoint Identifier (TEID) of the MME_A40/CPF_A 140/AMF_A 240, or both of them. Furthermore, the IP address ofthe MME_A 40/CPF_A 140/AMF_A 240 and the TEID of the MME_A 40/CPF_A140/AMF_A 240 may be stored independently of each other. The MME F-TEIDmay be identification information for user data, or identificationinformation for control information.

The SGW F-TEID is information for identifying the SGW_A 35. The SGWF-TEID may include an IP address of the SGW_A 35, a TEID of the SGW_A35, or both of them. The IP address of the SGW_A 35 and the TEID of theSGW_A 35 may be stored independently of each other. The SGW F-TEID maybe identification information for user data, or identificationinformation for control information.

The PCW F-TEID is information for identifying the PGW_A 30/UPGW_A130/SMF_A 230/UPF_A 235. The PGW F-TEID may include an IP address of thePGW_A 30/UPGW_A 130/SMF_A 230/UPF_A 235, a TEID of the PGW_A 30/UPGW_A130/SMF_A 230/UPF_A 235, or both of them. In addition, the IP address ofthe PGW_A 30/UPGW_A 130/SMF_A 230/UPF_A 235 and the TEID of the PGW_A30/UPGW_A 130/SMF_A 230/UPF_A 235 may be stored independently of eachother. The PGW F-TEID may be identification information for user data,or identification information for control information.

The eNB F-TEID is information for identifying the eNB_A 45. The eNBF-TEID may include an IP address of the eNB_A 45, a TEID of the eNB_A45, or both of them. The IP address of the eNB_A 45 and the TEID of theSGW_A 35 may be stored independently of each other. The eNB F-TEID maybe identification information for user data, or identificationinformation for control information.

The APN may be identification information for identifying the corenetwork and an external network such as the DN. Furthermore, the APN canalso be used as information for selecting a gateway such as the PGW_A30/UPGW_A 130/UPF_A 235 for connecting the core network_A 90. Note thatthe APN may be a Data Network Name (DNN). Therefore, the APN may berepresented by a DNN, or the DNN may be represented by the APN.

Note that the APN may be identification information for identifying sucha gateway, or identification information for identifying an externalnetwork such as the DN. Note that, in a case that multiple gatewaysconnecting the core network and the DN are deployed, there may bemultiple gateways that can be selected according to the APN.Furthermore, one gateway may be selected among such multiple gateways byanother method using identification information other than the APN.

The UE Radio Access Capability is identification information indicatinga radio access capability of the UE_A 10. The UE Network Capabilityincludes an algorithm of security supported by the UE_A 10 and a keyderivation function. The MS Network Capability is information including,in the UE_A 10 having a function of a GERAN_A 25 and/or a UTRAN_A 20,one or more pieces of information necessary for an SGSN_A 42. The AccessRestriction is registration information for access restriction. The eNBAddress is an IP address of the eNB_A 45. The MME UE S1AP ID isinformation for identifying the UE_A 10 in the MME_A 40/CPF_A 140/AMF_A240. The eNB UE S1AP ID is information for identifying the UE_A 10 inthe eNB_A 45.

The APN in Use is an APN recently used. The APN in Use may be DataNetwork Identifier. This APN may include identification information ofthe network and identification information of a default operator.Furthermore, the APN in Use may be information for identifying a DN withwhich the PDU session is established.

The Assigned Session Type is information indicating a PDU session type.The Assigned Session Type may be Assigned PDN Type. The PDU session typemay be IP, or non-IP. Furthermore, in a case that the PDU session typeis IP, information indicating a PDN type assigned by the network may befurther included. Note that the Assigned Session Type may be IPv6, orIPv4v6.

Unless otherwise specifically described, the IP Address refers to the IPaddress assigned to the UE. The IP address may be an IPv4 address, anIPv6 address, an IPv6 prefix, or an Interface ID. Note that in a casethat the Assigned Session Type indicates non-IP, an element of the IPAddress may not be included.

The DN ID is identification information for identifying the corenetwork_B 190 and an external network such as the DN. Furthermore, theDN ID can also be used as information for selecting a gateway such asthe UPGW_A 130 or the PF_A 235 connecting the core network_B 190.

Note that the DN ID may be identification information for identifyingsuch a gateway, or identification information for identifying anexternal network such as the DN. Note that, in a case that multiplegateways connecting the core network_B 190 and the DN are deployed,there may be multiple gateways that can be selected according to the DNID. Furthermore, one gateway may be selected among such multiplegateways by another method using identification information other thanthe DN ID.

Furthermore, the DN ID may be information equivalent to the APN, ordifferent from the APN. Note that in a case that the DN ID is theinformation different from the APN, each apparatus may manageinformation indicating correspondence between the DN ID and the APN,perform a procedure to inquire the APN by using the DN ID, or perform aprocedure to inquire the DN ID by using the APN.

SCEF ID is an IP address of an SCEF_A 46 used in the PDU session. TheDefault Bearer is information acquired and/or created in a case that aPDU session is established and is EPS bearer identification informationfor identifying a default bearer associated with the PDU session.

The EPS Bearer ID is identification information of the EPS bearer. TheEPS Bearer ID may be identification information for identifyingSignalling Radio Bearer (SRB) and/or Control-plane Radio bearer (CRB),or identification information for identifying Data Radio Bearer (DRB).The Transaction Identifier (TI) is identification information foridentifying a bidirectional message flow (Transaction). Note that theEPS Bearer ID may be EPS bearer identification information foridentifying a dedicated bearer. Therefore, the EPS bearer ID may beidentification information for identifying the EPS bearer different fromthe default bearer. The TFT indicates all packet filters associated withthe EPS bearer. The TFT is information for identifying some pieces ofuser data to be transmitted and/or received, and thus, the UE_A 10 usesthe EPS bearer associated with the TFT to transmit and/or receive theuser data identified by the TFT. In still other words, the UE_A 10 usesa Radio Bearer (RB) associated with the TFT to transmit and/or receivethe user data identified by the TFT. The TFT may associate the user datasuch as application data to be transmitted and/or received with anappropriate transfer path, and may be identification information foridentifying the application data. The UE_A 10 may use the default bearerto transmit and/or receive the user data which cannot be identified bythe TFT. The UE_A 10 may store in advance the TFT associated with thedefault bearer.

The Default Bearer is EPS bearer identification information foridentifying a default bearer associated with a PDU session. Note thatthe EPS bearer may be a logical communication path established betweenthe UE_A 10 and the PGW_A 30/UPGW_A 130/UPF_A 235, or a communicationpath constituting the PDN connection/PDU session. Furthermore, the EPSbearer may be a default bearer, or a dedicated bearer. Furthermore, theEPS bearer may include an RB established between the UE_A 10 and thebase station and/or the access point in the access network. Furthermore,the RB and the EPS bearer may be associated with each other on aone-to-one basis. Therefore, identification information of the RB may beassociated with the identification information of the EPS bearer on aone-to-one basis, or may be the same identification information as theidentification information of the EPS bearer. Note that the RB may be anSRB and/or a CRB, or a DRB. Furthermore, the Default Bearer may beinformation that the UE_A 10 and/or the SGW_A 35 and/or the PGW_A30/UPGW_A 130/SMF_A 230/UPF_A 235 acquire from the core network in acase that the PDU session is established. Note that the default beareris an EPS bearer first established during the PDN connection/PDUsession, and is such an EPS bearer that only one bearer can beestablished during one PDN connection/PDU session. The default bearermay be an EPS bearer that can be used for communication of user data notassociated with the TFT. The dedicated bearer is an EPS bearerestablished after the default, bearer is established during the PDNconnection/PDU session, and is such an EPS bearer that multiple bearerscan be established during one PUN connection/PDU session. The dedicatedbearer is an EPS bearer that can be used for communication of user datanot associated with the TFT.

User Identity is information for identifying a subscriber. The UserIdentity may be an IMSI, or an MSISDN. Furthermore, the User Identitymay also be identification information other than the IMSI or theMSISDN. Serving Node Information is information for identifying theMME_A 40/CPF_A 140/AMF_A 240 used in a PDU session, and may be an IPaddress of the MME_A 40/CPF_A 140/AMF_A 240.

The eNB Address is an IP address of the eNB_A 45. The eNB ID isinformation for identifying the UE in the eNB_A 45. MME Address is an IPaddress of the MME_A 40/CPF_A 140/AMF_A 240. MME ID is information foridentifying the MME_A 40/CPF_A 140/AMF_A 240. The NR node_Address is anIP address of the NR node_A 122. The NR node ID is information foridentifying the NR node_A 122. The WAG Address is an IP address of theWAG. The WAG ID is information for identifying the WAG.

The anchor or anchor point is a UFP with a gateway function for the PDUsession with the DN. The UPF used as an anchor point may be a PDUsession anchor or an anchor.

The SSC mode indicates the mode of Session and Service Continuity (SSC)supported by a system and/or each apparatus in the 5GC. To be morespecific, the SSC mode may be a mode indicating the type of the sessionand service continuity supported by a PDU session established betweenthe UE_A 10 and the anchor point). Here, the anchor point may be theUPGW or may be the UPF_A 235. Note that the SSC mode may be a modeindicating a type of the session and service continuity configured foreach PDU session. The SSC mode may be configured to include three modesof SSC mode 1, SSC mode 2, and SSC mode 3. The SSC mode is associatedwith the anchor point and cannot be changed while the PDU session isestablished.

Furthermore, the SSC mode 1 in the present embodiment is a mode ofsession and service continuity in which the same UPF is continuouslymaintained as the anchor point regardless of the access technology suchas the Radio Access Technology (RAT) and the cell used in a case thatthe UE_A 10 connects to a network. To be more specific, the SSC mode 1may be a mode in which even in a case that the mobility of the UE_A 10occurs, the session and service continuity is achieved without changingthe anchor point used by the established PDU session.

Furthermore, the SSC mode 2 in the present embodiment is a mode ofsession and service continuity in which, in a case that the PDU sessioncontains an anchor point associated with one SSC mode 2, the PDU sessionis released and subsequently a PDU session is established. Moreparticularly, the SSC mode 2 is a mode that, in a case that a relocationof the anchor point occurs, the PDU session is temporarily deleted andthen a new PDU session is established.

Furthermore, the SSC mode 2 is a mode of the session and servicecontinuity in which the same UPF is continuously maintained as theanchor point only in a serving area of the UPF. To be more specific, theSSC mode 2 may be a mode in which as long as the UE_A 10 is in theserving area of the UPF, the session and service continuity is achievedwithout changing the UPF used by the established PDU session.Furthermore, the SSC mode 2 may be a mode in which in a case that themobility of the UE_A 10 such as mobility of exit of the UE_A 10 from theserving area of the UPF occurs, the session and service continuity isachieved by changing the UPF used by the established PDU session.

Here, the serving area of the TUPF may be an area in which one UPF canprovide a session and service continuity function, or a subset of theaccess network such as the RAT or the cell used in a case that the UE_A10 connects to a network. The subset of the access network may be anetwork including one or multiple RATs and/or cells, or may be the TA.

Furthermore, the SSC mode 3 in the present embodiment is a mode ofsession and service continuity in which, without releasing the PDUsession between the UE and the anchor point, a PDU session can beestablished between a new anchor point and the UE for the same DN.

Furthermore, the SSC mode 3 is a mode of the session and servicecontinuity that allows a new PDU session and/or communication path to beestablished via a new UPF for the same DN before disconnecting the PDUsession and/or the communication path established between the UE_A 10and the UPF. The SSC mode 3 may be a mode of session and servicecontinuity that allows the UE_A 10 to be multi-homed.

And/or, the SSC mode 3 may be a mode that allows session and servicecontinuity using multiple PDU sessions and/or the UPFs associated withthe PDU sessions. In other words, in the case of the SSC mode 3, eachapparatus may achieve the session and service continuity using themultiple PDU sessions, or may achieve the session and service continuityusing the multiple TUPFs.

Here, in the case that each apparatus establishes a new PDU sessionand/or communication path, a new UPF may be selected by the network, ora new UPF may be an optimal UPF for a place at which the UE_A 10connects to the network. In a case that the multiple PDU sessions and/orthe UPFs used by the PDU sessions are effective, the UE_A 10 maycorrelate the application and/or flow to the PDU sessions for whichcommunications have been newly established, immediately or based on thecompletion of the communications.

1.3. Description of Initial Procedure

Next, before describing detailed processes of an initial procedure inthe present embodiment, in order to avoid redundant descriptions,terminology specific to the present embodiment and primaryidentification information used in each procedure will be describedbeforehand.

“Network” in the present embodiment refers to at least sonic of theaccess network_A 20/B 80, the access network_B 80/120, the corenetwork_A 90, the core network_B 190, the DN_A 5, and the PDN_A 6.Additionally, one or more apparatuses included in at least some of theaccess network_A 20/B 80, the access network_B 80/120, the corenetwork_A 90, the core network_B 190, the DN_A 5, and the PDN_A 6 mayalso be referred to as a network or network apparatuses. Specifically,the expression “the network performs transmission and/or reception of amessage and/or performs a procedure” signifies that “an apparatus(network apparatus) in the network performs transmission and/orreception of a message and/or performs a procedure”.

The Session Management (SM) message (also referred to as theNon-Access-Stratum (NAS) SM message or an SM message) in the presentembodiment may be a NAS message used in a procedure for the SM (alsoreferred to as a session management procedure or an SM procedure), ormay be a control message transmitted and/or received between the UE_A 10and the SMF_A 230 via the AMF_A 240. Furthermore, the SM message mayinclude a PDU session establishment request message, a PDU sessionestablishment accept message, a PDU session completion message, a PDUsession reject message, a PDU session modification request message, aPDU session modification accept message, a PDU session modificationreject message, and the like. The procedure for SM may include a PDUsession establishment procedure, a PDU session modification procedure,and the like.

A Tracking Area (also referred to as a TA) in the present embodiment isa range that can be represented by location information of the UE_A 10managed by the core network, and may include one or more cells, forexample. Furthermore, the TA may be a range in which a control messagesuch as a paging message is broadcast, or a range in which the UE_A 10can move without performing a handover procedure.

A TA list in the present embodiment is a list including one or more TAsallocated to the UE_A 10 by the network. Note that, while the UE_A 10 ismoving within the one or more TAs included in the TA list, the UE_A 10can move without performing the registration procedure. In other words,the TA list may be an information group indicating an area in which theUE_A 10 can move without performing the registration procedure.

A Network Slice in the present embodiment is a logical network thatprovides particular network capabilities and network performance.Hereinafter, the network slice is also referred to as a NW slice.

The Network Slice Instance (NSI) in the present embodiment is an entityof each of one or multiple Network Slices configured in the corenetwork_B 190. Additionally, the NSI in the present embodiment mayinclude a virtual Network Function (NF) generated using a Network SliceTemplate (NST). Here, the NST is associated with a resource request forproviding a required communication service or capability, and is alogical expression of one or multiple Network Functions (NFs).Specifically, the NSI may be an aggregation including multiple NFs inthe core network_B 190. The NSI may be a logical network configured toclassify the user data delivered through a service or the like. Thenetwork slice may include at least one or more NFs. The NF included inthe network slice may be an apparatus shared by another network slice orotherwise. The UE_A 10 and/or an apparatus in the network can beassigned to one or multiple network slices, based on registrationinformation such as NSSAI and/or S-NSSAI and/or UE usage type and/or oneor multiple network slice type IDs and/or one or multiple NS IDs, and/orAPNs.

The S-NSSAI in the present embodiment is an abbreviation for SingleNetwork Slice Selection Assistance information, and is information foridentifying a network slice. The S-NSSAI may include an SST(Slice/Service type) and an SD (Slice Differentiator). The S-NSSAI mayinclude only the SST or may include both SST and SD. Here, the SST isinformation indicating an operation of a network slice expected in termsof function and service. Additionally, the SD may be information thatcomplements the SST in a case that one piece of NSI is selected frommultiple pieces of NSI indicated by the SST. The S-NSSAI may beinformation unique to each Public Land Mobile Network (PLMN), or may bestandard information shared between PLMNs, or may be information that isunique to each network operator and that varies with the PLMN.

More specifically, the SST and/or SD may be standard information(Standard Value) common among the PLMNs or may be information (NonStandard Value) that is unique to each network operator and that varieswith the PLMN. Additionally, the network may store one or multiplepieces of S-NSSAI in the registration information of the UE_A 10 as thedefault S-NSSAI.

The Single Network Slice Selection Assistance information (NSSAI) in thepresent embodiment is a group of S-NSSAI, Each piece of S-NSSAI includedin the NSSAI is information that assists the access network or the corenetwork in selecting the NSI. The UE_A 10 may store the NSSAI granted bythe network for each PLMN. Additionally, the NSSAI may be informationused to select the AMF_A 240.

The operator A network according to the present embodiment is a networkoperated by a network operator A (operator A). Here, for example, theoperator A may have deployed a NW slice common to an operator Bdescribed below.

The operator B network according to the present embodiment is a networkoperated by a network operator B (operator B). Here, for example, theoperator B may have deployed a NW slice common to the operator A.

The first NW slice in the present embodiment is an NW slice to which anestablished PDU session belongs in a case that the UE connects to aparticular DN. Note that for example, the first NW slice may be an NWslice managed in the operator A network, or a NW slice that is commonlymanaged in the operator B network.

The second NW slice in the present embodiment is an NW slice to whichanother PDU session for connecting to the DN to which the PDU sessionbelonging to the first NW slice is connected belongs to. Note that thefirst NW slice and the second NW slice may be operated by the sameoperator or may be operated by different operators.

The equivalent PLMN in the present embodiment is a PLMN treated as thesame PLMN as any PLMN in the network.

The Dedicated Core Network (DCN) in the present embodiment is one ormultiple specific subscriber type dedicated core networks configured inthe core network_A 90. Specifically, a DCN for a UE registered as aMachine to Machine (M2M) communication function user may be configuredin the core network_A 90, for example. In addition, a default DCN for aUE with no proper DCN may be configured in the core network_A 90.Furthermore, in the DCN, at least one or more MMES_40 or SGSNs_A 42 maybe located, and further, at least one or more SGWs_A 35, PGWs_A 30 orPCRFs_A 60 may be located. The DCN may be identified by the DCN ID, andthe UE may be assigned to one DCN, based on the information such as theUE usage type and/or DCN ID.

The first timer in the present embodiment is a timer configured tomanage the initiation of a procedure for session management, such as thePDU session establishment procedure, and/or transmission of a SessionManagement (SM) message such as a PDU session establishment requestmessage, and may be information indicating a value of a back-off timerfor managing the behavior of the session management. Hereinafter, thefirst timer and/or the back-off timer may be referred to as a timer.While the first timer is running, the initiation of the procedure forthe session management and/or the transmission and/or reception of theSM message for each apparatus may be prohibited. Note that the firsttimer may be configured in association with at least one of thecongestion control unit applied by the NW and/or the congestion controlunit identified by the UE. For example, the first timer may beconfigured in at least one unit of an APN/DNN unit, and/or anidentification information unit indicating one or more NW slices, and/ora rejection cause value unit in the session management procedure, and/ora session unit in which a rejection is indicated in the sessionmanagement procedure, and/or a PTI unit for the session managementprocedure.

The SM message may be an NAS message used in a procedure for the sessionmanagement, or may be a control message transmitted and/or receivedbetween the UE_A 10 and the SMF_A 230 via the AMF_A 240. Furthermore,the SM message may include a PDU session establishment request message,a PDU session establishment accept message, a PDU session completionmessage, a PDU session reject message, a PDU session modificationrequest message, a PDU session modification accept message, a PDUsession modification reject message, and the like. Furthermore, theprocedure for the session management may include the PDU sessionestablishment procedure, the PDU session modification procedure, and thelike. Additionally, in these procedures, a back-off timer value may beincluded in each message received by the UE_A 10. The UE may configure aback-off timer received from the NW as a first timer, or may otherwiseconfigure a timer value or configure a random value. Additionally, in acase that the back-off timer received from the NW includes multipleback-off timers, the UE may manage multiple “first timers” correspondingto the multiple back-off timers, or select one timer value from themultiple back-off timer values received by the NW based on a policy heldby the UE, and configure the selected timer value as the first timer formanagement. For example, in a case that the UE receives two back-offtimer values, the UE configures the back-off timer values received fromthe NW as the “first timer #1” and the “first timer #2” respectively formanagement. Alternatively, one value may be selected from the multipleback-off timer values received from the NW based on the policy held bythe UE and set as the first timer for management.

In a case of receiving multiple back-off timer values from the NW, theUE_A 10 may manage multiple “first timers” corresponding to the multipleback-off timers. Here, for a distinction among the multiple “firsttimers” received by the UE_A 10, the following description may include,for example, the designation “first timer #1” or “first timer #2”. Notethat the multiple back-off timers may be acquired in a single sessionmanagement procedure, or may be acquired in a different, another sessionmanagement procedure.

Here, the first timer may be a back-off timer configured for multipleassociated NW slices based on information for identifying one NW sliceas described above, to inhibit reconnection, or a back-off timerconfigured in units of a combination of the APN/DNN and one NW slice, toinhibit reconnection. However, no such limitation is intended, and thefirst timer may be a back-off timer configured in units of a combinationof the APN/DNN and multiple associated NW slices based on informationfor identifying one NW slice, to inhibit reconnection.

Re-attempt information in the present embodiment is information providedby the network (NW) to indicates to the UE_A 10 whether to allowreconnection to a rejected PDU session using the same identificationinformation. Note that the re-attempt information may be configured foreach UTRAN access, E-UTRAN access, NR access, or slice information.Furthermore, the re-attempt information specified in the access unit maybe allowed to reconnect to the network based on an access change. There-attempt information specified in the slice unit may be designatedwith slice information different from the slice information of therejected slice, and reconnection using the specified slice informationmay be allowed.

A network slice association rule in the present embodiment is a rulethat associates information for identifying multiple network slices.Note that the network slice association rule may be received in the PDUsession reject message or may be previously configured in the UE_A 10.Furthermore, as the network slice association rule, the newest one inthe UE_A 10 may be applied. In contrast, the UE_A 10 may performbehavior based on the latest network slice association rule. Forexample, with the network slice association rule initially configuredwith the UE_A 10, in a case of receiving a new network slice associationrule in the PDU session reject message, the UE_A 10 may update thenetwork slice association rule held in the UE_A 10.

A priority management rule for the back-off timer in the presentembodiment is a rule configured in the UE_A 10 to collectively manage,in a single back-off timer, multiple back-off timers activated inmultiple PDU sessions. For example, in a case that conflicting oroverlapping different types of congestion control are applied and thatthe UE holds multiple back-off timers, the UE_A 10 may collectivelymanage multiple back-off timers based on the priority management rulefor the back-off timers. Note that a pattern in which different types ofcongestion control conflict or overlap corresponds to a case wherecongestion control based solely on the DNN and different types ofcongestion control based on both the DNN and the slice information areapplied at the same time and that, in this case, congestion controlbased solely on DNN is given top priority. Note that the prioritymanagement rule for the back-off timer may not be limited to this rule.The back-off timer may be a first timer included in the PDU sessionreject message.

A first state in the present embodiment is a state in which eachapparatus has completed the registration procedure and the PDU sessionestablishment procedure, and in which one or more of the first to fourthtypes of congestion control are applied to the UE_A 10 and/or eachapparatus. Here, in the UE_A 10 and/or each apparatus, the UE_A 10 maybe registered in the network (RM-REGISTERED state) due to completion ofthe registration procedure, and the completion of the PDU sessionestablishment procedure may correspond to reception of the PD sessionestablishment reject message from the network by the UE_A 10.

The congestion control in the present embodiment includes one or moretypes of congestion control included in the first to fourth types ofcongestion control. Note that the control of the UE by the NW isachieved by the congestion control recognized by the first timer and theUE and that the UE may store association of such information.

The first type of congestion control in the present embodiment indicatescontrol signal congestion control directed to a DNN parameter. Forexample, in a case that congestion on DNN #A is detected in the NW andthat the NW recognizes a UE-initiated session management requestdirected only to the DNN #A parameter, the NW can apply the first typeof congestion control. Note that, even in a case that the UE-initiatedsession management request includes no DNN information, on theinitiative of the NW, the default DNN may be selected as a congestioncontrol target. Alternatively, even in a case of recognizing that theUE-initiated session management request includes DNN #A and S-NSSAI #A,the NW may apply the first type of congestion control. In a case thatthe first type of congestion control is applied, the UE may inhibit theUE-initiated session management request intended only for DNN #A.

In other words, the first type of congestion control in the presentembodiment is control signal congestion control intended for the DNN andmay be congestion control resulting from a congested state ofconnectivity to the DNN. For example, the first type of congestioncontrol may be congestion control for restricting connection to DNN #Ain all of the connectivity. Here, the connection to the DNN #A in all ofthe connectivity may be connection to DNN #A in connectivity using anyS-NSSAI available to the UE, and may be connection to DNN #A via networkslices to which the UE can connect. Furthermore, the connection to theDNN #A in all of the connectivity may include connectivity to DNN #Awith no intermediary of a network slice.

The second type of congestion control in the present embodimentindicates control signal congestion control directed to an S-NSSIparameter. For example, in a case that the control signal congestion onS-NSSAI #A. is detected in the NW and that the NW recognizes aUE-initiated session management. request directed only to the S-NSSAI #Aparameter, the NW can apply the second type of congestion control. In acase that the second type of congestion control is applied, the UE mayinhibit the UE-initiated session management request directed only toS-NSSAI #A.

In other words, the second type of congestion control in the presentembodiment is control signal congestion control intended for the S-NSSAIand may be congestion control resulting from a congested state of thenetwork slice selected based on the S-NSSAI. For example, the secondtype of congestion control may be congestion control for restricting allconnections based on S-NSSAI #A. That is, the second type of congestioncontrol may be congestion control for restricting connection to all DNNsvia network slices selected by using S-NSSAI #A.

The third type of congestion control in the present embodiment indicatescontrol signal congestion control directed to the DNN and S-NSSAIparameters. For example, in a case that control signal congestion on DNN#A and control signal congestion on S-NSSAI #A are detected at the sametime in the NW and that the NW recognizes a UE-initiated sessionmanagement request directed to the DNN #A and S-NSSAI #A parameters, theNW may apply the third type of congestion control. Note that even in acase that the UE-initiated session management request includes noinformation indicating the DNN, then on the initiative of the NW, thedefault DNN may be selected also as a congestion control target. In acase that the third type of congestion control is applied, the UE mayinhibit the UE-initiated session management request directed to the DNN#A and S-NSSAI #A parameters.

In other words, the third type of congestion control in the presentembodiment is control signal congestion control intended for the DNN andS-NSSAI parameters, and may be congestion control resulting from acongested state of the connectivity to the DNN via the network sliceselected based on the S-NSSAI. For example, the third type of congestioncontrol may be congestion control for restricting the connection to DNN#A included in the connectivity based on S-NSSAI #A.

The fourth type of congestion control in the present embodimentindicates control signal congestion control directed to at least one ofthe DNN and/or S-NSSAI parameter. For example, in a case that controlsignal congestion on DNN #A and control signal congestion on S-NSSAI #Aare simultaneously detected in the NW and that the NW recognizes aUE-initiated session management request directed to at least one of theDNN #A and/or S-NSSAI #A parameter, the NW may apply the fourth type ofcongestion control. Note that even in a case that the UE-initiatedsession management request includes no information indicating the DNN,then on the initiative of the NW, the default DNN may be selected alsoas a congestion control target. In a case that the fourth type ofcongestion control is applied, the UE may inhibit the UE-initiatedsession management request directed to at least one of the DNN #A and/orS-NSSAI #A parameter.

In other words, the fourth type of congestion control in the presentembodiment is control signal congestion control intended for the DNN andS-NSSAI parameters, and may be congestion control resulting from acongested state of the network slice selected based on the S-NSSAI andthe connectivity to the DNN. For example, the fourth type of congestioncontrol is congestion control for restricting all connections based onS-NSSAI #A and may be congestion control for restricting the connectionto DNN #A in all of the connectivity. That is, the fourth type ofcongestion control is congestion control for restricting the connectionto all DNNs via network slices selected based on S-NSSAI #A, and may becongestion control for restricting the connection to DNN #A in all ofthe connectivity. Here, the connection to the DNN #A in all of theconnectivity may be connection to DNN #A in connectivity using anyS-NSSAI available to the UE, and may be connection to DNN #A via networkslices to which the UE can connect. Furthermore, the connection to theDNN #A in all of the connectivity may include connectivity to DNN #Awith no intermediary of a network slice.

Thus, the fourth type of congestion control using DNN #A and S-NSSAI #Aas parameters may be congestion control that simultaneously performs thefirst type of congestion control using DNN #A as a parameter and thesecond type of congestion control using S-NSSAI #A as a parameter.

First behavior in the present embodiment is behavior in which the UEstores slice information transmitted in the first PDU sessionestablishment request message in association with the transmitted PDUsession identification information. In the first behavior, the UE maystore slice information transmitted in the first PDU sessionestablishment request message or may store slice information received ina case that the first PDU session establishment request is rejected.

Second behavior in the present embodiment is behavior in which the UEtransmits a PDU session establishment request for connecting to anAPN/DNN identical to the APN/DNN included in the first PDU sessionestablishment request using another slice information different from theslice information specified in the first PDU session establishment.Specifically, the second behavior may be such that in a case that theback-off timer value the UE has received from the network is zero orinvalid, the UE uses slice information separate from the sliceinformation specified in the first PDU session establishment to transmita PDU session establishment request for connecting to an APN/DNNidentical to the APN/DNN included in the first PDU session establishmentrequest. Additionally, the second behavior may be as follows: in a casethat the first PDU session is rejected because wireless access to theparticular PLMN to which the designated APN/DNN is connected is notsupported, or in a case that the first PDU session is rejected for atemporary cause, the UE uses slice information separate from the sliceinformation specified in the first PDU session establishment to transmita PDU session establishment request for connecting to an APN/DNNidentical to the APN/DNN included in the first PDU session establishmentrequest.

Third behavior in the present embodiment is behavior in which, in a casethat the PDU session establishment request is rejected, the UE transmitsno new PDU session establishment request with the identicalidentification information until the first timer expires. Specifically,the third behavior may be behavior in which, in a case that the back-offtimer value received from the network is not zero or invalid, the UEtransmits no new PDU session establishment request with the identicalidentification information until the first timer expires. Here, theidentical identification information may mean whether the first piece ofidentification information and/or the second piece of identificationinformation carried in the new PDU session establishment request isidentical to the first piece of identification information and/or thesecond piece of identification information transmitted in the rejectedPDU session establishment request.

Additionally, the behavior may be as follows: in a case that anotherPLMN or another NW slice is selected and that a rejection cause for aconfiguration failure for network operation is received, and that theback-off timer is active that has been received in a case that the firstPDU session establishment request is rejected, no new PDU sessionestablishment request using the identical identification information istransmitted until the first timer expires.

In particular, the PDU session in which no new PDU session establishmentrequest in the third behavior is transmitted may be a PDU session towhich congestion control associated with the first timer is applied.More specifically, the third behavior may be behavior such that no newPDU session establishment request is transmitted for the PDU sessionbased on the connectivity corresponding to the type of the congestioncontrol associated with the first timer, the PDU session using the DNNand/or S-NSSAI associated with the congestion control. Note that theprocessing in which the present behavior prohibits the UE may includethe initiation of the procedure for the session management including thePDU session establishment request and/or transmission and/or receptionof an SM message.

Fourth behavior in the present embodiment is behavior in which, in acase that the PDU session establishment request is rejected, the UEtransmits no new PDU session establishment request carrying no sliceinformation or DNN/APN information until the first timer expires.Specifically, the fourth behavior may be behavior in which, in a casethat the back-off timer received from the network is not zero orinvalid, the UE transmits no new PDU session establishment request,carrying no slice information or DNN/APN information until the firsttimer expires.

Fifth behavior in the present embodiment is behavior in which, in a casethat the PDU session establishment request is rejected, the UE transmitsno new PDU session establishment request with the identicalidentification information. Specifically, the fifth behavior may bebehavior in which, in a case that the UE and the network differ in a PDPtype supported and are served by equivalent PLMNs, the UE transmits nonew PDU session establishment request with the identical identificationinformation.

Sixth behavior in the present embodiment is behavior in which, in a casethat the PDU session establishment request is rejected, the UE transmitsa new PDU session establishment request as an initial procedure by usingthe identical identification information. Specifically, the sixthbehavior may be behavior in which, in a case that the first PDU sessionestablishment request is rejected because no target PDN session contextis present in handover from non-3GPP access, the UE transmits a new PDUsession establishment request as an initial procedure by using theidentical identification information.

Seventh behavior in the present embodiment is behavior in which, in acase of selecting another NW slice in a procedure for selecting a PLMN,the UE continues the back-off timer received in a case that the last PDUsession establishment request is rejected. Specifically, the seventhbehavior may be behavior in which, in a case that the first PDU sessionestablishment request is rejected, in a case that PLMN selection hasbeen performed and that an NW slice can be specified that is the same asthe NW slice specified in the first PDU session establishment request inthe selected PLMN, the UE continues the back-off timer received in acase that the first PDU session establishment request is rejected.

Eighth behavior in the present embodiment is behavior in which the UEconfigures a value notified from the network or a value previouslyconfigured for the UE as a first timer value. Specifically, the eighthbehavior may be behavior in which the UE configures, as the first timervalue, the back-off timer value received in the reject notification forthe first PDU session establishment request, or configures, as the firsttimer value, a value previously configured or held in the UE. Note thatthe case where the timer previously configured or held in the UE isconfigured as the first timer value may be limited to a case where theUE is served by an HPLMN or an equivalent PLMN.

Ninth behavior in the present embodiment is behavior in which, in a casethat the PDU session establishment request is rejected, the UE transmitsno new PDU session establishment request until terminal power on/off orremoval and insertion of a Universal Subscriber Identity Module (USIM).Specifically, in the ninth behavior, in a case that the back-off timerreceived from the network is invalid or that the first PDU sessionrejection cause is a difference in PDP type between the UE and thenetwork, the UE transmits no new PDU session establishment request untilterminal power on/off or removal and insertion of the USIM.Additionally, the ninth behavior may be behavior in which, in a casethat the first PDU session is rejected because the designated APN/DNN isnot supported by the radio in the connected PLMN and that no informationelement of the back-off timer is obtained from the network, with noRe-attempt information obtained or in a case that PDU sessionreconnection to an equivalent PLMN is allowed, no new PDU sessionestablishment request is transmitted in the connected PLMN untilterminal power on/off or removal and insertion of the USIM.Additionally, the ninth behavior may be behavior in which, in a casethat the first PDU session is rejected because the designated APN/DNN isnot supported by the radio in the connected PLMN and that no informationelement of the back-off timer is obtained from the network, with noRe-attempt information obtained or in a case that PDU sessionreconnection to an equivalent PLMN is not allowed, no new PDU sessionestablishment request is transmitted in the connected PLMN untilterminal power on/off or removal and insertion of the USIM.Additionally, the ninth behavior may be behavior in which, in a casethat the first PDU session is rejected because the designated APN/DNN isnot supported by the radio in the connected PLMN and that the back-offtimer from the network is not zero or invalid, no new PDU sessionestablishment request is transmitted until terminal power on/off orremoval and insertion of the USIM. In addition, the ninth behavior maybe behavior in which, in a case that the first PDU session is rejectedbecause the designated APN/DNN is not supported by the radio in theconnected PLMN and that the back-off timer from the network is invalid,no new PDU session establishment request is transmitted until terminalpower on/off or removal and insertion of the USIM.

Tenth behavior in the present embodiment is behavior in which, in a casethat the PDU session establishment request is rejected, the UE transmitsa new PDU session establishment request. Specifically, the 10th behaviormay be behavior in which, in a case that the back-off timer receivedfrom the network is zero or in a case that the first PDU sessionestablishment request is rejected for a temporary cause and thatback-off timer information element itself is not notified from thenetwork, the UE transmits a new PDU session establishment request.Additionally, the 10th behavior may be behavior in which, in a case thatanother PLMN or another NW slice is selected and that the first PDUsession establishment request is rejected for a temporary cause and thatthe back-off timer is not activated for the target APN/DNN in theselected PLMN or in a case that the back-off timer received from thenetwork is invalid, a new PDU session establishment request istransmitted. Additionally, the 10th behavior may be behavior in which,in a case that the first PDU session establishment request is rejecteddue to a difference in DPP type between the UE and the network and that,in a case that a different PLMN is selected, no Re-attempt informationis received or a PLMN that is not included in an equivalent PLMN list isselected, or in a case that the PDP type is changed or in a case thatterminal power on/off or removal and insertion of the USIM areperformed, a new PDU session establishment request is transmitted.Additionally, the 10th behavior may be behavior in which, in a case thatthe first PDU session is rejected because the designated APN/DNN is notsupported by the radio in the connected PLMN and that the back-off timernotified from the network is zero, a new PDU session establishmentrequest is transmitted.

Eleventh behavior in the present embodiment is behavior in which the UEignores the first timer and the Re-attempt information. Specifically,the 11th behavior may be behavior in which, in a case that the first PDUsession establishment request is rejected because no target PDN sessioncontext is present in handover from non-3GPP access or that the firstPDU session establishment is rejected because the number of bearersprovided in the PUN connection reaches a maximum allowable value, the UEignores the first timer and the Re-attempt information.

Twelfth behavior in the present embodiment is behavior in which, basedon information for identifying one NW slice received in the rejectnotification for the first PDU session establishment request, the UEdetermines information for identifying multiple associated NW slices,and based on information for identifying one NW slice, the UE inhibitsreconnection to the multiple associated NW slices. Specifically, the 12behavior may be behavior that the UE derives information to identifyanother NW slice associated with information for identifying a NW slicenotified with the first PDU session establishment request reject basedon the network slice association rule. Note that the network sliceassociation rule may be previously configured in the UE or may benotified from the network in a reject notification for the PDU sessionestablishment.

Thirteenth behavior in the present embodiment may be behavior in which,in a case that multiple, different types of congestion control areactivated for establishment of one or multiple PDU sessions by theidentical UE and that multiple timers are provided from the network, theUE manages the timers based on the priority management rule for theback-off timer. For example, a first PDU session establishment requestfor a combination of DNN_1 and slice_1 from the UE is subjected tocongestion control based on both DNN and slice information, and the UEreceives a first timer #1. Furthermore, the UE makes a second PDUsession establishment request for a combination of DNN_1 and slice_2,and is subjected to congestion control based only on the DNN, andreceives a first timer #2. At this time, the UE is based on the prioritymanagement rule for the back-off timer, and the behavior of PDU sessionreestablishment by the UE may be managed by the first timer #2, which isprioritized. Specifically, the value of the timer held by the UE may beoverwritten with the timer value generated by prioritized congestioncontrol.

Fourteenth behavior in the present embodiment may be behavior in which,in a case that multiple, different types of congestion control areapplied for establishment of one or multiple PDU sessions by theidentical UE and that multiple timers are provided from the network, theUE manages the timers for each session management instance (PDU sessionunit). For example, in a case that first PDU session establishment of acombination of DNN #1 and slice #1 by the UE is subjected to congestionbased on both DNN and slice information, the UE manages the back-offtimer value of interest as the first timer #1. Thereafter, furthermore,in a case that, at a time when the UE attempts to establish a PDUsession for a combination of DNN #1 and slice #2 as a second PDUsession, the establishment is subjected to congestion based only on theDNN, the UE manages the back-off timer value of interest as the firsttimer #2. At this time, the UE simultaneously manages multiple timers(here, the first timer #1 and the first timer #2). Specifically, the UEmanages the timers in units of the session management instance/PDUsession. Alternatively, in a case of simultaneously receiving multipletimers in one session management procedure, the UE simultaneouslymanages the back-off timers of interest in the units of congestioncontrol identified by the UE.

Fifteenth behavior in the present embodiment may be behavior in whichthe UE_A 10 performs first identification processing for identifyingwhich of the first to fourth types of congestion control is to beapplied and second identification processing for identifying the DNNand/or the S-NSSAI associated with the applied congestion control. Notethat the first identification processing may include identificationbased on one or more pieces of identification information from at leasta first to a fourth pieces of identification information and/or one ormore pieces of identification information from at least an 11th to an18th pieces of identification information. Similarly, the secondidentification processing may include identification based on one ormore pieces of identification information from at least the first to thefourth pieces of identification information and/or one or more pieces ofidentification information from at least the 11th to the 18th pieces ofidentification information.

An example of the first identification processing will be describedbelow. In the first identification processing, the type of congestioncontrol applied in a case that any one of the following cases or acombination of two or more of the following cases are satisfied may beidentified as the first type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to the first type of congestion control.

At least a case where the 16th piece of identification information is avalue corresponding to the first type of congestion control.

At least a case where the 14th piece of identification informationincludes information indicating the first type of congestion control.

At least a case where the 17th piece of identification informationincludes only the DNN and does not include the S-NSSAI.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the first type of congestion control and the second type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to thesecond type of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the first type of congestion control and the fourth type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to thefourth type of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying the identificationinformation for one of the first type of congestion control, the secondtype of congestion control, and the fourth type of congestion controland that the 16th piece of identification information is informationenabling configuration, for the 16th piece of identificationinformation, of only the value corresponding to the second type ofcongestion control and the value corresponding to the fourth type ofcongestion control, then at least the 16th piece of identificationinformation is not received.

However, the present invention is not limited to the example describedabove, and the UE_A 10 may perform identification based on one or morepieces of identification information from at least the first to thefourth pieces of identification information and/or one piece ofidentification information from at least the 11th to the 18th pieces ofidentification information or a combination of two or more pieces ofidentification information.

In the first identification processing, the type of congestion controlapplied in a case that any one of the following cases or a combinationof two or more of the following cases are satisfied may be identified asthe second type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to the second type of congestion control.

At least a case where the 16th piece of identification information is avalue corresponding to the second type of congestion control.

At least a case where the 14th piece of identification informationincludes information indicating the second type of congestion control.

At least a case where the 17th piece of identification informationincludes only the S-NSSAI and does not include the DNN.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the first type of congestion control and the second type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to the firsttype of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control and the third type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to the thirdtype of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control, the third type ofcongestion control, and the fourth type of congestion control and thatthe 16th piece of identification information is information enablingconfiguration, for the 16th piece of identification information, of onlythe value corresponding to the third type of congestion control and thevalue corresponding to the fourth type of congestion control, then atleast the 16th piece of identification information is not received.

However, the present invention is not limited to the example describedabove, and the UE_A 10 may perform identification based on one or morepieces of identification information from at least the first to thefourth pieces of identification information and/or one piece ofidentification information from at least the 11th to the 18th pieces ofidentification information or a combination of two or more pieces ofidentification information.

In the first identification processing, the type of congestion controlapplied in a case that any one of the following cases or a combinationof two or more of the following cases are satisfied may be identified asthe third type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to the third type of congestion control.

At least a case where the 16th piece of identification information is avalue corresponding to the third type of congestion control.

At least a case where the 14th piece of identification informationincludes information indicating the third type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to multiple types of congestion control includingthe third type of congestion control and not including the fourth typeof congestion control and where the 17th piece of identificationinformation includes the S-NSSAI and the DNN.

Case where, in a case that the 16th piece of identification informationis information for identifying identification information for one of thethird type of congestion control and the fourth type of congestioncontrol and that the 16th piece of identification information isinformation enabling configuration, for the 16th piece of identificationinformation, of only the value corresponding to the fourth type ofcongestion control, then at least the 16th piece of identificationinformation is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control and the third type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to thesecond type of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control, the third type ofcongestion control, and the fourth type of congestion control and thatthe 16th piece of identification information is information enablingconfiguration, for the 16th piece of identification information, of onlythe value corresponding to the second type of congestion control and thevalue corresponding to the fourth type of congestion control, then atleast the 16th piece of identification information is not received.

However, the present invention is not limited to the example describedabove, and the UE_A 10 may perform identification based on one or morepieces of identification information from at least the first to thefourth pieces of identification information and/or one piece ofidentification information from at least the 11th to the 18th pieces ofidentification information or a combination of two or more pieces ofidentification information.

In the first identification process, the type of congestion controlapplied in a case that any one of the following cases or a combinationof two or more of the following cases are satisfied may be identified asthe fourth type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to the fourth type of congestion control.

At least a case where the 16th piece of identification information is avalue corresponding to the fourth type of congestion control.

At least a case where the 14th piece of identification informationincludes information indicating the fourth type of congestion control.

At least a case where the 15th piece of identification information is avalue corresponding to multiple types of congestion control includingthe fourth type of congestion control and not including the third typeof congestion control and where the 17th piece of identificationinformation includes the S-NSSAI and the DNN.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the third type of congestion control and the fourth type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to the thirdtype of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control and the fourth type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to thesecond type of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the first type of congestion control and the fourth type ofcongestion control and that the 16th piece of identification informationis information enabling configuration, for the 16th piece ofidentification information, of only the value corresponding to the firsttype of congestion control, then at least the 16th piece ofidentification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the second type of congestion control, the third type ofcongestion control and the fourth type of congestion control and thatthe 16th piece of identification information is information enablingconfiguration, for the 16th piece of identification information, of onlythe value corresponding to the second type of congestion control and thevalue corresponding to the third type of congestion control, then atleast the 16th piece of identification information is not received.

A case where, in a case that the 16th piece of identificationinformation is information for identifying identification informationfor one of the first type of congestion control, the second type ofcongestion control and the fourth type of congestion control and thatthe 16th piece of identification information is information enablingconfiguration, for the 16th piece of identification information, of onlythe value corresponding to the first type of congestion control and thevalue corresponding to the second type of congestion control, then atleast the 16th piece of identification information is not received.

However, the present invention is not limited to the example describedabove, and the UE_A 10 may perform identification based on one or morepieces of identification information from at least the first to thefourth pieces of identification information and/or one piece ofidentification information from at least the 11th to the 18th pieces ofidentification information or a combination of two or more pieces ofidentification information, or using any other means.

As described above, the type of congestion control may be identified bythe first identification processing.

Now, an example of the second identification processing will bedescribed. Note that the second identification processing may beprocessing for identifying the DINN and/or S-NSSAI corresponding to thetype of the congestion control identified by the first identificationprocessing.

More specifically, the DNN corresponding to the first type of congestioncontrol, the third type of congestion control, and the fourth type ofcongestion control may be determined based on the 12th piece ofidentification information. And/or the DNN corresponding to the firsttype of congestion control, the third type of congestion control, andthe fourth type of congestion control may be determined based on the17th piece of identification information. And/or the DNN correspondingto the first type of congestion control, the third type of congestioncontrol, and the fourth type of congestion control may be determinedbased on the second piece of identification information.

Accordingly, the DNN corresponding to the first type of congestioncontrol, the third type of congestion control, and the fourth type ofcongestion control may be the DNN indicated by the 12th piece ofidentification information. And/or the DNN corresponding to the firsttype of congestion control, the third type of congestion control, andthe fourth type of congestion control may be the DNN included in the17th piece of identification information. And/or the DNN correspondingto the first type of congestion control, the third type of congestioncontrol, and the fourth type of congestion control may be the DNNindicated by the second piece of identification information.

Additionally, the S-NSSAI corresponding to the second type of congestioncontrol, the third type of congestion control, and the fourth type ofcongestion control may be determined based on the 17th piece ofidentification information. And/or the DNN corresponding to the firsttype of congestion control, the third type of congestion control, andthe fourth type of congestion control may be determined based on thefirst piece of identification information.

Thus, the DNN corresponding to the first type of congestion control, thethird type of congestion control, and the fourth type of congestioncontrol may be the S-NSSAI indicated by the 17th piece of identificationinformation. And/or the DNN corresponding to the first type ofcongestion control, the third type of congestion control, and the fourthtype of congestion control may be the S-NSSAI included in the firstpiece of identification information.

However, the present invention is not limited to the example describedabove, and the UE_A 10 may perform identification based on one or morepieces of identification information from at least the first to thefourth pieces of identification information and/or one piece ofidentification information from at least the 11th to the 18th pieces ofidentification information or a combination of two or more pieces ofidentification information, or using any other means.

Based on the above-described 15th behavior, the UE_A 10 may identify thecongestion control that the core network_B 190 applies to the UE_A 10.In other words, the UE_A 10 may identify the corresponding type ofcongestion control and the corresponding S-NSSAI and/or DNN as appliedcongestion control based on the 15th behavior. Note that the UE_A 10 maystore and manage one or multiple pieces of identification informationfrom the first to fourth pieces of identification information and the11th to 18th pieces of identification information in association withthe applied congestion control, Here, the third piece of identificationinformation, and/or the fourth piece of identification information,and/or the 13th piece of identification information may be stored andmanaged as information for identifying the applied congestion control.

The 16th behavior in the present embodiment is behavior in which, in acase that an NW-initiated session management procedure is performedwhile the first timer is active, the UE stops the first timer.

Here, the 16th behavior may be behavior in which, for example, in a casethat multiple first timers are active, the UE determines, based on the21st piece of identification information, one of the active first timersto be stopped and stops the determined first timer. And/or the 16thbehavior may be behavior in which the first timer associated withcongestion control identified by the 17th behavior is stopped. Notethat, in a case that multiple types of congestion control are identifiedby the 17th behavior, the timers associated with the respective types ofcongestion control may each be stopped.

The 17th behavior in the present embodiment may be behavior in which theUE identifies, based on reception of a control message transmitted bythe core network, the congestion control that is included in the one ormultiple types of congestion control applied by the UE and for which theapplication is to be stopped. For example, the UE may identify, based onthe 21st identification information, the congestion control for whichthe application is to be stopped or changed.

Specifically, as described above, in the fourth step of processing, theUE stores, for example, the third piece of identification information,and/or the fourth piece of identification information, and/or the 13thpiece of identification information and/or the like as information foridentifying congestion control, and may identify the congestion controlfor which the identification information matches the 13th piece ofidentification information included in the 21st identificationinformation may be identified as the congestion control for which theapplication is to be stopped.

And/or the UE may identify the congestion control for which theapplication is to be stopped, based on one piece of identificationinformation or a combination of multiple pieces of identificationinformation from the 11th to 18th pieces of identification informationincluded in the 21st piece of identification information. Here, thedetails of the identification method may be the same as theidentification processing in the 15th behavior described in the fourthstep of processing in an example of the PDU session establishmentprocedure described below. That is, the UE may identify the congestioncontrol to be stopped, by using a method similar to the method foridentifying the applied congestion control.

Note that the UE may identify multiple types of congestion control forwhich the application is to be stopped. Hereinafter, a method will bedescribed that includes determining the congestion control identified byusing the above-described method to be the first type of congestioncontrol and identifying the second type of congestion control differentfrom the first type of congestion control.

For example, the UE may identify, as the second type of congestioncontrol, the congestion control associated with the same DNN as the DNNassociated with the first type of congestion control. And/or the UE mayidentify the congestion control associated with the same S-NSSAI as theS-NSSAI associated with the first type of congestion control as thesecond type of congestion control. Note that the configuration may besuch that identifying multiple types of congestion control for which theapplication is to be stopped is performed only in a case that the firsttype of congestion control and/or the second type of congestion controlis of a particular type of congestion control.

Specifically, in a case that the first type of congestion control is oneof the first to fourth types of congestion control, the UE may identifythe second type of congestion control. And/or in identifying the secondtype of congestion control, the UE may identify the second type ofcongestion control in a case that the congestion control to be searchedfor is one of the first to fourth types of congestion control. Note thatit is sufficient that what type of the first type of congestion controland/or the second type of identification information enables multipletypes of congestion control to be identified may be initially configuredin the core network and/or the UE. Note that the number of particulartypes of congestion control for which identification is allowed need notbe specified as one and that multiple types of congestion control may beconfigured.

The first piece of identification information in the present embodimentis information for identifying belonging to a first NW slice. In otherwords, the first piece of identification information may be informationindicating that the UE desires to establish a PDU session belonging tothe first NW slice. Specifically, for example, the first piece ofidentification information may be information for identifying the firstNW slice. Note that the slice information may be identificationinformation indicating a specific S-NSSAI. Note that the first piece ofidentification information may be information for identifying aparticular NW slice in the operator A network, or may be information foridentifying identical NW slices in common in operator B (other operatorsother than operator A). Furthermore, the first piece of identificationinformation may be information for identifying the first NW sliceconfigured from the HPLMN, information for identifying the first NWslice obtained from the AMF in the registration procedure, orinformation for identifying the first NW slice granted from the network.Furthermore, the first piece of identification information may beinformation for identifying the first NW slice stored for each PLMN.

The second piece of identification information in the present embodimentmay the Data Network Name (DNN) and may be used to identify the DataNetwork (DN).

The third piece of identification information in the present embodimentmay be a PDU Session ID and may be information used to identify the PDUSession.

The fourth piece of identification information in the present embodimentmay a Procedure transaction identity (PTI) and may be information foridentifying, as a single group, transmission and/or reception of asequence of messages for a particular session management procedure andmay further be information used to identify and/or distinguish thetransmission and/or reception from transmission and/or reception ofother sequences of session management related messages.

The 11th piece of identification information in the present embodimentmay be information indicating that a request for PDU sessionestablishment or a request for PDU session modification is rejected.Note that the request for PDU session establishment or the request forPDU session modification is a request made by the UE and includes theDNN and/or S-NSSAI. That is, the 11th piece of identificationinformation may be information indicating that the NW rejects theestablishment request or modification request for the PDU sessioncorresponding to the DNN and/or S-NSSA.

Additionally, the NW may also indicate the congestion control to the UEby transmitting at least one of the 12th to 18th pieces ofidentification information to the UE along with the 11th identificationinformation. In other words, the NW may notify the UE of the congestioncontrol corresponding to one piece of identification information or acombination of multiple pieces of identification information from the12th to 18th pieces of identification information. On the other hand,the UE may identify the congestion control corresponding to one piece ofidentification information or a combination of multiple pieces ofidentification information from the 12th to 18th pieces ofidentification information, and perform processing based on theidentified congestion control. Specifically, the UE may initiatecounting the first timers associated with the identified congestioncontrol. Note that the timer value of the first timer may be determinedby using the 14th piece of identification information or a timer valueconfigured by another method such as the use of a value previously savedby the UE, or a random value may be configured as the tinier value.

The 12th piece of identification information in the present embodimentmay be DNN not granted by the network or may be information indicatingthat the DNN identified by the second piece of identificationinformation has not been granted, Furthermore, the 12th identificationinformation may be the same DNN as that of the second piece ofidentification information.

The 13th piece of identification information in the present embodimentmay be a PDU Session ID and/or PTI, and may be a PDU session ID and/orPTI not granted by the network, or may be information indicating thatthe PDU session ID and/or PTI identified by the third piece ofidentification information has not been granted. Furthermore, the PDUSession ID of the 13th piece of identification information may be thesame PDU session ID as that of the third piece of identificationinformation. Additionally, the PTI of the 13th piece of identificationinformation may be the same PTI as that of the fourth piece ofidentification information.

Here, the 13th piece of identification information may be used asinformation for identifying the congestion control that the NW notifiesto the UE based on the rejection of PDU session establishment. In otherwords, the UE may store and manage the 13th piece of identificationinformation in association with the congestion control performed basedon the 15th behavior and use the 13th piece of identificationinformation as information for identifying the performed congestioncontrol. Note that the information for identifying the congestioncontrol may include a combination of the 13th piece of identificationinformation and one or more pieces of identification information fromthe 14th to 18th pieces of identification information.

The 14th piece of identification information in the present embodimentmay be information indicating the value of the back-off timer. In otherwords, the back-off timer may be a value indicating an effective periodof the congestion control that the NW notifies to the UE based on therejection of PDU session establishment. In other words, the UE may usethe 14th piece of identification information as the timer value in the15th behavior performed in response to the reception of the 14th pieceof identification information. Furthermore, the 14th piece ofidentification information may include information for identifying thetype of congestion control in addition to the timer value. Specifically,the 14th piece of identification information may include information foridentifying which of the first to fourth types of congestion controlcorresponds to the congestion control of interest. For example, theinformation for identifying the congestion control type may be a timername that identifies each type of congestion control, or a flag thatidentifies each type of congestion control. No such limitation isintended, and any other identification method may be used, such asidentification based on the location in the control message where theinformation is stored.

The 15th identification information in the present embodiment isinformation indicating one or more Cause Values indicating the cause ofrejection of the present procedure. In other words, the cause value maybe information indicating the congestion control applied to the presentprocedure by the NW or information indicating a cause value for thecause of rejection of the present procedure applied by the NW, otherthan congestion control.

Note that the cause value may be information for identifying which ofthe first to fourth type of congestion control the NW notifies to the UEbased on the rejection of PDU session establishment. In this case, theNW may transmit a different value depending on each of the first tofourth types of congestion control, to the UE as the cause value. The UEmay understand, in advance, the meaning of the values transmitted ascause values, and in the 15th behavior, may identify, based at least onthe 15th piece of identification information, which of the first tofourth types of congestion control corresponds to the congestion controlof interest.

Alternatively, the cause value may be information for identifyingwhether the congestion control that the NW notifies to the UE based onthe rejection of PDU session establishment is the first type ofcongestion control or one of the second, third, and fourth types ofcongestion control. In this case, depending on a case where thecongestion control to be notified is the first type of congestioncontrol or a case where the congestion control to be notified is one ofthe second, third, and fourth types of congestion control, the NW maytransmit a different value to the UE as a cause value. The UE mayunderstand, in advance, the meaning of the values transmitted as causevalues, and in the 15th behavior, may identify, based at least on the15th piece of identification information, whether the congestion controlto be notified corresponds to the first type of congestion control orthe second, third, and fourth types of congestion control.

Alternatively, the cause value may be information for identifyingwhether the congestion control that the NW notifies to the UE based onthe rejection of PDU session establishment is the first type ofcongestion control, the second type of congestion control, or one of thethird and fourth types of congestion control. In this case, depending ona case where the congestion control to be notified is the first type ofcongestion control, a case where the congestion control to be notifiedis the second type of congestion control, or a case where the congestioncontrol to be notified is one of the third and fourth types ofcongestion control, the NW may transmit a different value to the UE as acause value. The UE may understand, in advance, the meaning of thevalues transmitted as cause values, and in the 15th behavior, mayidentify, based at least on the 15th piece of identificationinformation, whether the congestion control to be notified is the firsttype of congestion control, the second type of congestion control, orone of the third and fourth types of congestion control.

Alternatively, the cause value may be information for identifyingwhether the congestion control that the NW notifies to the UE based onthe rejection of PDU session establishment corresponds to the first orsecond type of congestion control or the third or fourth type ofcongestion control. In this case, depending on a case where thecongestion control to be notified is the first or second type ofcongestion control or a case where the congestion control to be notifiedis the third or fourth type of congestion control, the NW may transmit adifferent value to the UE as a cause value. The UE may understand, inadvance, the meaning of the values transmitted as cause values, and inthe 15th behavior, may identify, based at least on the 15th piece ofidentification information, whether the congestion control to benotified is the first or second type of congestion control or the thirdor fourth type of congestion control.

Alternatively, the cause value may be information for identifyingwhether the congestion control that the NW notifies to the UE based onthe rejection of PDU session establishment corresponds to the second orthird type of congestion control or the first or fourth type ofcongestion control. In this case, depending on a case where thecongestion control to be notified is the second or third type ofcongestion control or a case where the congestion control to be notifiedis the first or fourth type of congestion control, the NW may transmit adifferent value to the UE as a cause value. The UE may understand, inadvance, the meaning of the values transmitted as cause values, and inthe 15th behavior, may identify, based at least on the 15th piece ofidentification information, whether the congestion control to benotified is the second or third type of congestion control or the firstor fourth type of congestion control.

Alternatively, the cause value may be information for identifyingwhether the congestion control that the NW notifies to the UE based onthe rejection of PDU session establishment corresponds to the second orfourth type of congestion control or the first or third type ofcongestion control. In this case, depending on a case where thecongestion control to be notified is the second or fourth type ofcongestion control or a case where the congestion control to be notifiedis the first or third type of congestion control, the NW may transmit adifferent value to the UE as a cause value. The UE may understand, inadvance, the meaning of the values transmitted as cause values, and inthe 15th behavior, may identify, based at least on the 15th piece ofidentification information, whether the congestion control to benotified is the second or fourth type of congestion control or the firstor third type of congestion control.

Alternatively, the cause value may be information indicating that the NWperforms congestion control for the UE based on the rejection of PDUsession establishment. In other words, the cause value may beinformation for causing one of the first to fourth types of congestioncontrol to be performed for the UE. In this case, the cause value neednot be information allowing certain congestion control to be identified.

Note that in the present embodiment, in a case that the third type ofcongestion control is not performed, the implications, corresponding tothe third type of congestion control, of the cause value in the 15thpiece of identification information as described above are unnecessary,and the cause value in the 15th piece of identification information maycorrespond to the above description from which the processing,description, and implications related to the third type of congestioncontrol are omitted. Additionally, in the present embodiment, in a casethat the fourth type of congestion control is not performed, theimplications, corresponding to the fourth type of congestion control, ofthe cause value in the 15th piece of identification information asdescribed above are unnecessary, and the cause value in the 15th pieceof identification information may correspond to the above descriptionfrom which the processing, description, and implications related to thefourth type of congestion control are omitted.

As a more detailed example, the 15th piece of identification informationfor identifying the first type of congestion control may be a causevalue indicating Insufficient resources. The 15th piece ofidentification information for identifying the second type of congestioncontrol may be a cause value indicating Insufficient resources forspecific slice. The 15th piece of identification information foridentifying the third type of congestion control may be a cause valueindicating Insufficient resources for specific slice and DNN.

In this way, the 15th piece of identification information may beinformation allowing the type of congestion control to be identified,and indicating which type of congestion control corresponds to theback-off timer and/or the back-off timer value indicated by the 14thpiece of identification information.

Accordingly, the UE_A 10 may identify the type of congestion controlbased on the 15th piece of identification information. Furthermore, theUE_A 10 may determine, based on the 15th piece of identificationinformation, which type of congestion control corresponds to theback-off timer and/or the back-off timer value indicated by the 14thpiece of identification information.

The 16th piece of identification information in the present embodimentis one or more pieces of Indication information indicating that thepresent procedure has been rejected. In other words, the Indicationinformation may be information indicating the congestion control appliedby the NW to the present procedure. The NW may indicate the congestioncontrol applied by the NW based on the 16th piece of identificationinformation.

For example, the Indication information may be information indicatingwhich of two or more types of congestion control included in the firstto fourth types of congestion control is restricted for the UE by theNW. Accordingly, the NW may transmit, as indication information, a valueassociated with restrictive management applied to the UE. The UE mayunderstand, in advance, the meaning of the values transmitted asIndication information, and in the 15th behavior, may identify, based atleast on the 16th piece of identification information, which of thefirst to fourth types of congestion control is to be restricted. Here,the two or more types of congestion control included in the first tofourth types of congestion control are each congestion control that canbe identified by using the Indication information, and the two or moretypes of congestion control to be identified may be all four types ofcongestion control, the first and second types of congestion control,the third and fourth types of congestion control, the second to fourthtypes of congestion control, or any other combination.

Note that the Indication information does not necessarily require thevalues corresponding to all the types of congestion control to beidentified. For example, as long as values of the Indication informationare assigned to and associated with the respective types of congestioncontrol except for congestion control A, the value of the Indicationinformation need not necessarily be configured for the congestioncontrol A. In this case, the NW and the UE can identify the first typeof congestion control based on the lack of transmission and/or receptionof the Indication information. Note that the congestion control A may beany of the first to fourth types of congestion control.

In addition, in a case that the congestion control is notified to the UEbased on transmission of the PDU session establishment reject message,the Identification may or may not be included depending on the types ofthe first to fourth types of congestion controls. In other words,depending on the type of congestion control, the NW may use theIdentification information as information indicating the congestioncontrol, and for a certain type of congestion control, instead of theIdentification information, any other type of identification informationmay be as information indicating the congestion control.

Note that in the present embodiment, in a case that the third type ofcongestion control is not performed, the implications, corresponding tothe third type of congestion control, of the Indication information inthe 16th piece of identification information as described above areunnecessary, and the Indication information in the 16th piece ofidentification information may correspond to the above description fromwhich the processing, description, and implications related to the thirdtype of congestion control are omitted. Additionally, in the presentembodiment, in a case that the fourth type of congestion control is notperformed, the implications, corresponding to the fourth type ofcongestion control, of the Indication information in the 16th piece ofidentification information as described above are unnecessary, and theIndication information in the 16th piece of identification informationmay correspond to the above description from which the processing,description, and implications related to the fourth type of congestioncontrol are omitted.

The 17th identification information in the present embodiment is one ormore pieces of Value information indicating that the present procedurehas been rejected. In other words, the Value Information may beinformation indicating the congestion control applied to the presentprocedure by the NW. Note that the 17th piece of identificationinformation may be information including at least one of identificationinformation for identifying one or multiple NW slices included in the18th piece of identification information and/or the 12th piece ofidentification information.

The NW may indicate the congestion control applied by the NW based onthe 17th piece of identification information. In other words, the NW mayindicate which of the first to fourth types of congestion control hasbeen applied, based on the 17th piece of identification information.Furthermore, based on the 17th piece of identification information, theNW may indicate the DNN and/or S-NSSAI to be subjected to the congestioncontrol applied to the UE based on the transmission of the PDU sessionreject message. For example, in a case that the 17th piece ofidentification information is only DNN #1, the information may indicatethat the first type of congestion control directed to DNN #1 is ineffect. In a case that the 17th piece of identification information isonly S-NSSAI #1, the information may indicate that the second type ofcongestion control directed to S-NSSAI #1. is in effect. In a case thatthe 17th piece of information includes DNN #1 and S-NSSAI #1, then theinformation may indicate that the third or fourth type of congestioncontrol directed to at least one of DNN #1 and/or S-NSSAI #1 is ineffect.

Note that the 17th piece of identification information need notnecessarily be information allowing identification of which of the firstto fourth types of congestion control has been applied and that the 17thpiece of identification information may be information indicating theDNN and/or S-NSSAI to be subjected to the congestion control identifiedby any other means, for example, based on any other type ofidentification information.

The 18th piece of identification information in the present embodimentmay be information indicating that a request for establishment of a PDUsession belonging to the first NW slice has been rejected or informationindicating that a request for establishment of the PDU session belongingto the first NW slice or for PDU session modification has not beengranted. Here, the first NW slice may be a NW slice determined by thefirst piece of identification information or may be a different NWslice. Furthermore, the 18th piece of identification information may beinformation indicating that establishment of a PDU session belonging tothe first NW slice in the DN identified by the 12th piece ofidentification information is not granted or information indicating thatestablishment of a PDU session belonging to the first NW slice the PDUsession identified by the 13th piece of identification information isnot granted. Furthermore, the 11th piece of identification informationmay be information indicating non-granting of establishment of a PDUsession belonging to the first slice in a registration area and/or atracking area to which the UE_A 10 currently belongs or non-granting ofestablishment of a PDU session belonging to the first NW slice in theaccess network to which the UE_A 10 is connected. Furthermore, the 11thpiece of identification information may be identification informationfor identifying one or multiple NW slices determining the NW slice towhich the rejected PDU session request belongs. Furthermore, the 18thpiece of identification information may be identification informationindicating auxiliary information for the radio access system to selectthe appropriate MME in a case that the UE switches a connectiondestination to the EPS. Note that the auxiliary information may beinformation indicating the DCN ID. Furthermore, the 18th piece ofidentification information may be a network slice association rule thatis a rule for associating multiple pieces of slice information.

The 21st piece of identification information in the present embodimentmay be information used to stop one or multiple first timers activatedby the UE, or may be information indicating the first timer that isincluded in the first timers activated by the UE and that is to bestopped. Specifically, the 21st piece of identification information maybe information indicating the 13th piece of identification informationstored in the UE in association with the first timers. Furthermore, the21st piece of identification information may be information indicatingat least one of the 12th to 18th pieces of identification informationstored in the UE in association with the first timers.

Furthermore, the 21st piece of identification information may beinformation used to change the association between the first timerstored in the UE and information indicating at least one of the 13th to17th pieces of identification information. For example, in a case that,while the first timer inhibiting a UE-initiated session management for acombination of DNN #A and S-NSSAI #A is active, the UE receives anNW-initiated session management request including the 21st piece ofidentification information granting connection to DNN #A, the UE maychange the association target of the active timer to S-NSSAI #A only andrecognize that the UE-initiated session management request to DNN #A hasbeen granted. In other words, the 21st piece of identificationinformation may be information indicating that the congestion control ineffect at the time of reception of the 21st piece of identificationinformation is changed to another type of congestion control included inthe first to fourth types of congestion control.

Now, an initial procedure according to the present embodiment will bedescribed with reference to FIG. 9. Hereinafter, the initial procedureis also referred to as the present procedure, and the present procedureincludes the Registration procedure, the PDU session establishmentprocedure, and the network-initiated session management procedure.Details of the registration procedure, the PDU session establishmentprocedure, the network-initiated session management procedure will bedescribed below.

Specifically, with the apparatuses performing the registration procedure(S900), the UE_A 10 transitions to a state registered with the network(RM-REGISTERED state). Then, with the apparatuses performing the PDUsession establishment procedure (S902), the UE_A 10 establishes, via thecore network_B 190, a PDU session with the DN_A 5 providing a PDUconnection service, and then the apparatuses transition to the firststate (S904). Although the PDU session is assumed to be established viathe access network and the UPF_A 235, no such limitation is intended.That is, a UPF (UPF_C 239) different from the UPF_A 235 may be presentbetween the UPF_A 235 and the access network. At this time, the PDUsession is established via the access network, the UPF_C 239, and theUPF_A 235. Then, the apparatuses in the first state may perform thenetwork-initiated session management procedure at any time (S906).

Note that, in the registration procedure and/or the PDU sessionestablishment procedure and/or the network-initiated session managementprocedure, the apparatuses may exchange various pieces of capabilityinformation and/or various pieces of request information of therespective apparatuses with one another. Additionally, in a case ofperforming exchange of various pieces of information and/or negotiationof various requests in the registration procedure, each of theapparatuses may or may not perform exchange of various pieces ofinformation and/or negotiation of various requests in the PDU sessionestablishment procedure and/or the network-initiated session managementprocedure. Additionally, in a case of not performing exchange of variouspieces of information and/or negotiation of various requests in theregistration procedure, each of the apparatuses may perform exchange ofvarious pieces of information and/or negotiation of various requests inthe PDU session establishment procedure and/or the network-initiatedsession management procedure. Additionally, even in a case of performingexchange of various pieces of information and/or negotiation of variousrequests in the registration procedure, each of the apparatuses mayperform exchange of various pieces of information and/or negotiation ofvarious requests in the PDU session establishment procedure and/or thenetwork-initiated session management procedure.

In addition, each apparatus may perform the PDU session establishmentprocedure in the registration procedure or after the registrationprocedure is completed. Furthermore, in a case that the PDU sessionestablishment procedure is performed in the registration procedure, thePDU session establishment request message included in the registrationrequest message may be transmitted and/or received, and the PDU sessionestablishment accept message included in the registration accept messagemay be transmitted and/or received, a PDU session establishment completemessage included in a registration complete message may be transmittedand/or received, and a PDU session establishment reject message includedin a registration reject message may be transmitted and/or received. Inaddition, in a case that the PDU session establishment procedure isperformed during the registration procedure, based on the completion ofthe registration procedure, each apparatus may establish a PDU sessionor may transition to the state in which a PDU session is establishedbetween apparatuses.

Furthermore, each apparatus involved in the present procedure maytransmit and/or receive each control message described in the presentprocedure to transmit and/or receive one or more pieces ofidentification information included in each control message and storeeach piece of identification information transmitted and/or received asa context.

1.3.1. Overview of Registration Procedure

First, the following describes the overview of the registrationprocedure. The registration procedure is a procedure initiated by theUE_A 10 to register with a network (the access network and/or the corenetwork_B 190 and/or the DN_A 5). In a state in which the UE_A 10 is notregistered in the network, the UE_A 10 can perform the present procedureat any timing such as the timing of turning on power. In other words,the UE_A 10 may initiate the present procedure at any timing in anon-registered state (RM-DEREGISTERED state). In addition, eachapparatus may transition to a registered state (RM-REGISTERED state),based on the completion of the registration procedure.

Furthermore, the present procedure may be a procedure for updatinglocation registration information of the UE_A 10 in the network, forregularly notifying a state of the UE_A 10 from the UE_A 10 to thenetwork, and/or for updating particular parameters related to the UE_A10 in the network.

The UE_A 10 may initiate the present procedure in a case that the UE_A10 applies mobility across TAs. In other words, the UE_A 10 may initiatethe present procedure in a case that the UE_A 10 moves to a TA differentfrom a TA indicated in a TA list that the UE_A 10 holds. Furthermore,the UE_A 10 may initiate the present procedure in a case that a runningtimer expires. Furthermore, the UE_A 10 may initiate the presentprocedure in a case that a context of each apparatus needs to be updateddue to disconnection or disabling (also referred to as deactivation) ofa PDU session. Furthermore, the UE_10 may initiate the present procedurein a case that a change occurs in capability information and/orpreference concerning PDU session establishment of the UE_A 10.Furthermore, the UE_A 10 may initiate the present procedure regularly.Note that, besides the above, the UE_A 10 can perform the presentprocedure at any timing as long as a PDU session is established.

1.3.1.1 Example of Registration Procedure

An example procedure of performing the registration procedure will bedescribed with reference to FIG. 10. In the present section, the presentprocedure refers to the registration procedure. Each step of the presentprocedure will be described below.

First, the UE_A 10 transmits a Registration Request message to the AMF_A240 via the NR node (also referred to as the gNB)_A 122 and/or theng-eNB (S1000) (S1002) (S1004) to initiate the registration procedure.In addition, the UE_A 10 transmits a Session Management (SM) message(e.g., a PDU session establishment request message) included in theregistration request message, or transmits the SM message (e.g., the PDUsession establishment request message) along with the registrationrequest message to initiate a procedure for a session management (SM).such as the PDU session establishment procedure, during the registrationprocedure.

Specifically, the UE_A 10 transmits, to the NR node_A 122 and/or theng-eNB, a Radio Resource Control (RRC) message including theregistration request message (S1000). In a case of receiving the RRCmessage including the registration request message, the NR node_A 122and/or the ng-eNB retrieves the registration request message from theRRC message and selects the AMF_A 240 as a NF or a common CP function towhich the registration request message is routed (S1002). Here, the NRnode_A 122 and/or the ng-eNB may select the AMF_A 240 based oninformation included in the RRC message. The NR node_A 122 and/or theng-eNB transmits or transfers the registration request message to theselected AMF_A 240 (S1004).

Note that the registration request message is a Non-Access-Stratum (NAS)message transmitted and/or received on the N1 interface. In addition,the RRC message is a control message transmitted and/or received betweenthe UE_A 10 and the NR node_A 122 and/or the ng-eNB. Additionally, theNAS message is processed in a NAS layer, the RRC message is processed ina RRC layer, and the NAS layer is a layer higher than the RRC layer.

In addition, in a case that there are multiple NSIs requestingregistration, the UE_A 10 may transmit a registration request messagefor each of the NSIs, or may transmit multiple registration requestmessages included in one or more RRC messages. Furthermore, theabove-described multiple registration request messages included in oneor more RRC messages may be transmitted as one registration requestmessage.

In a case of receiving the registration request message and/or thecontrol message different from the registration request message, theAMF_A 240 performs a first condition determination. The first conditiondetermination is intended to determine whether or not the AMF_A 240accepts a request of the UE_A 10. In the first condition determination,the AMF_A 240 determines whether the first condition determination istrue or false. The AMF_A 240 initiates the procedure of (A) in thepresent procedure in a case that the first condition determination istrue (in other words, the network accepts the request of the UE_A 10),and initiates a procedure of (B) in the present procedure in a case thatthe first condition determination is false (in other words, the networkdoes not accept the request of the UE_A 10).

As follows, steps in a case that the first condition determination istrue, in other words, each step of the procedure of (A) in the presentprocedure will be described. The AMF_A 240 performs a fourth conditiondetermination, and initiates the procedure of (A) in the presentprocedure. The fourth condition determination is to determine whetherthe AMF_A 240 transmits and/or receives the SM message to/from the SMF_A230. In other words, the fourth condition determination may be intendedto determine whether or not the AMF_A 240 performs the PDU sessionestablishment procedure during the present procedure. In a case that thefourth condition determination is true (in other words, an SM message istransmitted and received between the AMF_A 240 and the SMF_A 230), theAMF_A 240 selects the SMF_A 230 and transmits and/or receives the SMmessage to and/or from the selected SMF_A 230. In a case that the fourthcondition determination is false (in other words, no SM message istransmitted or received between the AMF_A 240 and the SMF_A 230), theAMF_A 240 skips such processes (S1006). Note that in a case that theAMF_A 240 receives an SM message indicating rejection from the SMF_A230, the AMF_A 240 may terminate the procedure of (A) in the presentprocedure, and may initiate the procedure of (B) in the presentprocedure.

Furthermore, the AMF_A 240 transmits the Registration Accept message tothe UE_A 10 via the NR node_A 122 based on the reception of theregistration request message from the UE_A 10 and/or the completion ofthe transmission and/or reception of the SM message to/from the SMF_A230 (S1008). For example, in a case that the fourth conditiondetermination is true, the AMF_A 240 may transmit the registrationacceptance message based on the reception of the registration requestmessage from the UE_A 10. In a case that the fourth conditiondetermination is false, the AMF_A 240 may transmit the registrationacceptance message based on the completion of the transmission andreception of the SM message to and from the SMF_A 230. Here, theregistration accept message may be transmitted as a response message forthe registration request message. The registration accept message is aNAS message transmitted and received on the N1 interface, for example,the AMF_A 240 may transmit the registration accept message to the NRnode_A 122 as a control message for the N2 interface, and the NR node_A122 may receive and include the message in the RRC message, which isthen transmitted to the UE_A 10.

Furthermore, in a case that the fourth condition determination is true,the AMF_A 240 may include the SM message a PDU session establishmentaccept message) in the registration accept message and transmit theregistration accept message, or transmit the SM message (e.g., a PDUsession establishment accept message) along with the registration acceptmessage. This transmission method may be performed in a case that the SMmessage (e.g., the PDU session establishment request message) isincluded in the registration request message and the fourth conditiondetermination is true. Furthermore, the transmission method may beperformed in a case that the registration request message and the SMmessage (e.g., the PDU session establishment request message) areincluded and the fourth condition determination is true. The AMF_A 240may indicate that the procedure for SM has been accepted by performingsuch a transmission method.

The UE_A 10 receives the registration accept message via the NR node_A122 (S1008). The UE_A 10 receives the registration accept message andrecognizes the contents of various types of identification informationincluded in the registration accept message.

Then, the UE_A 10 transmits the Registration Complete message to theAMF_A 240 based on the registration accept message (S1010). Note that,in a case that the UE_A 10 has received an SM message such as a PDUsession establishment accept message, the UE_A 10 may transmit the SMmessage such as the PDU session establishment complete message includedin the registration complete message, or may include the SM messagetherein to indicate that the procedure for SM is completed. Here, theregistration complete message may be transmitted as a response messagefor the registration accept message. The registration complete messageis a NAS message transmitted and received on the N1 interface, forexample, the UE_A 10 may include the message in the RRC message andtransmit the RRC message to the NR node_A 122, and the NR node_A 122 mayreceive and transmit the message to the AMF_A 240 as an N2 interfacecontrol message.

The AMF_A 240 receives the registration complete message (S1010). Inaddition, each apparatus completes the procedure of (A) in the presentprocedure based on the transmission and/or reception of the registrationaccept message and/or the registration complete message.

Now, steps performed in a case that the first condition determination isfalse, in other words, each step of the procedure of (B) in the presentprocedure will be described. The AMF_A 240 transmits a RegistrationReject message to the UE_A 10 via the NR node_A 122 (S1012) to initiatethe procedure of (B) in the present procedure. Here, the registrationreject message may be a response message for the registration requestmessage. Additionally, the registration reject message is a NAS messagetransmitted and received on the N1 interface, for example, the AMF_A 240may transmit the registration reject message to the NR node_A 122 as acontrol message for the N2 interface, and the NR node_A 122 may receiveand include the message in the RRC message and transmit the RRC messageto the UE_A 10. Further, the registration reject message transmitted bythe AMF_A 240 is not limited thereto as long as it is a message forrejecting the request of the UE_A 10.

Note that the procedure of (B) in the present procedure may be initiatedin a case that the procedure of (A) in the present procedure iscanceled. Note that, in the procedure of (A), in a case that the fourthcondition determination is true, the AMF_A 240 may include, in theregistration reject message, the SM message, which indicates rejection,such as the PDU session establishment reject message and transmit theregistration reject message, or include, in the registration rejectmessage, the SM message indicating rejection to indicate that theprocedure for SM has been rejected. In that case, the UE_A 10 mayfurther receive the SM message, such as the PDU session establishmentreject message, that indicates rejection, or may recognize that theprocedure for SM has been rejected.

Furthermore, the UE_A 10 may recognize that a request of the UE_A 10 hasbeen rejected by receiving the registration reject message or notreceiving the registration accept message. Each apparatus completes theprocedure of (B) in the present procedure based on the transmissionand/or reception of the registration reject message.

Each apparatus completes the present procedure (registration procedure),based on the completion of the procedure of (A) or (B) in the presentprocedure. Note that each apparatus may transition to a state in whichthe UE_A 10 is registered with the network (RM_REGISTERED state) basedon the completion of the procedure of (A) in the present procedure, ormay maintain a state in which the UE_A 10 is not registered with thenetwork (RM_DEREGISTERED state) based on the completion of the procedureof (B) in the present procedure. Transition to each state of eachapparatus may be performed based on completion of the present procedure,or may be performed based on an establishment of a PDU session.

Furthermore, each apparatus may perform processing based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure.

Furthermore, the first condition determination may be performed based onidentification information, and/or subscriber information, and/or anoperator policy included in the registration request message. Forexample, the first condition determination may be true in a case thatthe network allows a request of the UE_A 10. In addition, the firstcondition determination may be false in a case that the network does notallow a request of the UE_A 10. Furthermore, the first conditiondetermination may be true in a case that the network of a destination ofregistration of the UE_A 10 and/or an apparatus in the network supportsa function requested by the UE_A 10, and may be false in a case that thenetwork and/or the apparatus does not support the function. Furthermore,the first condition determination may be true in a case that the networkdetermines that the network is congested, and may be false in a casethat the network determines that the network is not congested. Note thatconditions for determining whether the first condition determination istrue or false may not be limited to the above-described conditions.

The fourth condition determination may also be performed based onwhether AMF_A 240 has received an SM and may be performed based onwhether a SM message is included in the registration request message.For example, the fourth condition determination may be true in a casethat the AMF_A 240 has received the SM and/or the SM message is includedin the registration request message, and may be false in a case that theAMF_A 240 has not received the SM and/or the SM message is not includedin the registration request message. Note that conditions fordetermining whether the fourth condition determination is true or falsemay not be limited to the above-described conditions.

1.3.2. Overview of PDU Session Establishment Procedure

Next, an overview of the PDU session establishment procedure performedto establish a PDU session with the DN_A 5 will be described. The PDUsession establishment procedure is also referred to as a presentprocedure below. The present procedure is a procedure for each apparatusto establish the PDU session. Note that each apparatus may perform thepresent procedure in a state in which the registration procedure iscompleted or during the registration procedure. In addition, eachapparatus may initiate the present procedure in a registered state, ormay initiate the present procedure at any timing after the registrationprocedure. Each apparatus may establish the PDU session, based oncompletion of the PDU session establishment procedure. Furthermore, eachapparatus may perform the present procedure multiple times to establishmultiple PDU sessions.

1.3.2.1. Example of PDU Session Establishment Procedure

With reference to FIG. 11, an example of a procedure for performing thePDU session establishment procedure will be described. Each step of thepresent procedure will be described below. First, the UE_A 10 transmitsa PDU Session Establishment Request message to the core network_B viathe access network_B (S1100), and initiates the PDU sessionestablishment procedure.

Specifically, the UE_A 10 transmits the PDU session establishmentrequest message to the AMF_A 240 in the core network_B 190 via the NRnode_A 122 by using the N1 interface (S1100). The AMF_A receives the PDUsession establishment. request message, and performs a third conditiondetermination. The third condition determination is intended todetermine whether the AMF_A accepts the request of the UE_A 10. In thethird condition determination, the AMF_A determines whether a fifthcondition determination is true or false. In a case that the thirdcondition determination is true, the core network_B initiates processing#1 in the core network (S1101), and in a case that the third conditiondetermination is false, the core network_B initiates the procedure of(B) in the present procedure. Note that steps performed in a case thatthe third condition determination is false will be described below.Here, the processing #1 in the core network may be SMF selectionperformed by the AMF_A in the core network_B 190 and/or transmissionand/or reception of the PDU session establishment request messagebetween the AMF_A and the SMF_A.

The core network_B 190 initiates the processing #1 in the core network.In a case that, in the processing #1 in the core network, the AMF_A 240may select the SMF_A 230 as an NF to which the PDU session establishmentrequest message is routed, and may transmit or forward the PDU sessionestablishment request message to the selected SMF_A 230 by using the N11interface. Here, the AMF_A 240 may select the SMF_A 230 of the routingdestination based on the information included in the PDU sessionestablishment request message. More specifically, the AMF_A 240 mayselect the SMF_A 230 of the routing destination based on each piece ofidentification information acquired based on the reception of the PDUsession establishment request message, and/or the subscriberinformation, and/or the capability information of the network, and/orthe operator policy, and/or the state of the network, and/or the contextalready held by the AMF_A 240.

The PDU session establishment request message may be a NAS message. ThePDU session establishment request message only needs to be a messagerequesting the PDU session establishment and not limited to this.

Here, the UE_A 10 may include one or more of the first to fourth piecesof identification information in the PDU session establishment requestmessage, or may indicate the request of the UE_A 10 by inclusion ofthese pieces of identification information. Note that two or more ofthese pieces of identification information may be configured as one ormore pieces of identification information.

Furthermore, by including the first piece of identification informationand/or the second piece of identification information and/or the thirdpiece of identification information and/or the fourth piece ofidentification information in the PDU session establishment requestmessage for transmission, the UE_A 10 may request establishment of a PDUsession belonging to the network slice, indicate the network slice towhich the PDU session requested by the UE_A 10 belongs, or indicate thenetwork slice to which the PDU session is to belong.

More particularly, by transmitting the first piece of identificationinformation and the second piece of identification information inassociation with each other, the UE_A 10 may request establishment of aPDU session belonging to the network slice, the PDU session beingestablished with the DN identified by the second piece of identificationinformation, may indicate the network slice to which the PDU sessionrequested by the UE_A 10 belongs, or may indicate the network slice towhich the PDU session is to belong.

Furthermore, the UE_A 10 may combine and transmit two or more pieces ofidentification information from the first to fourth piece ofidentification information to make a request corresponding to acombination of the above-described matters. Note that the mattersindicated by the UE_A 10 by transmitting the identification informationneed not be limited to the above-described matters.

Note that the UE_A 10 may determine which of the first to fourth piecesof identification information is to be included in the PDU sessionestablishment request message, based on the capability information ofthe UE_A 10, and/or the policy such as the UE policy, and/or thepreference of the UE_A 10, and/or the application (higher layer). Notethat the determination performed by the UE_A 10 as to which piece ofidentification information is to be included in the PDU sessionestablishment request message is not limited to the determinationdescribed above.

The SMF_A 230 in the core network_B 190 receives the PDU sessionestablishment request message, and performs the third conditiondetermination. The third condition determination is intended todetermine whether the SMF_A 230 accepts the request of the UE_A 10. Inthe third condition determination, the SMF_A 230 determines whether thethird condition determination is true or false. In a case that the thirdcondition determination is true, the SMF_A 230 initiates the procedureof (A) in the present procedure, and in a case that the third conditiondetermination is false, the SMF_A 230 initiates the procedure of (B) inthe present procedure. Note that steps performed in a case that thethird condition determination is false will be described below.

Steps performed in a case that the third condition determination istrue, in other words, each step of the procedure of (A) in the presentprocedure will be described below. The SMF_A 230 selects the UPF_A 235,with which the PDU session is to be established, and performs an 11thcondition determination.

Here, the 11th condition determination is intended to determine whetheror not each apparatus performs processing #2 in the core network. Here,the processing #2 in the core network may include, for example,initiation and/or execution of the PDU session establishmentauthentication procedure by each apparatus, and/or transmission and/orreception of the Session Establishment request message between the SMF_Aand UPF_A in the core network_B 190, and/or transmission and/orreception of the Session Establishment response message (S1103). In the11th condition determination, the SMF_A 230 determines whether the 11thcondition determination is true or false. The SMF_A 230 initiates a PDUsession establishment authentication and/or authorization procedure in acase that the 11th condition determination is true, and omits the PDUsession establishment authentication and/or authorization procedure in acase that the 11th condition determination is false. Note that thedetails of the PDU session establishment authentication and/orauthorization procedure of the processing #2 in the core network will bedescribed below.

Then, the SMF_A 230 transmits the session establishment request messageto the selected UPF_A 235 based on the 11th condition determinationand/or completion of the PDU session establishment authentication and/orauthorization procedure, and initiates the procedure of (A) in thepresent procedure. Note that the SMF_A 230 may initiate the procedure of(B) in the present procedure without initiating the procedure of (A) inthe present procedure, based on the completion of the PDU sessionestablishment authentication and/or authorization procedure.

Here, the SMF_A 230 may select one or more UPFs_A 235 based on eachpiece of identification information acquired based on the reception ofthe PDU session establishment request message, and/or the capabilityinformation of the network, and/or the subscriber information, and/orthe operator policy, and/or the state of the network, and/or the contextalready held by the SMF_A 230. Note that in a case that multiple UPFs_A235 are selected, the SMF_A 230 may transmit the session establishmentrequest message to each UPF_A 235.

The UPF_A 235 receives the session establishment request message andcreates a context for the PDU session. Furthermore, the UPF_A 235transmits the session establishment response message to the SMF_A 230based on the reception of the session establishment request messageand/or the creation of a context for the PDU session. Furthermore, theSMF_A 230 receives a session establishment response message. Note thatthe session establishment request message and the session establishmentresponse message may be control messages transmitted and/or received onthe N4 interface. Further, the session establishment response messagemay be a response message to the session establishment request message.

Further, the SMF_A 230 may assign an address to be assigned to the UE_A10 based on the reception of the PDU session establishment requestmessage and/or the selection of the UPF_A 235 and/or the reception ofthe session establishment response message. Note that the SMF_A 230 mayassign the address to be assigned to the UE_A 10 during the PDU sessionestablishment procedure, or may assign the address after the completionof the PDU session establishment procedure.

Specifically, in a case that the SMF_A 230 assigns the IPv4 addresswithout using the DHCPv4, the SMF_A 230 may assign the address duringthe PDU session establishment procedure or may transmit the assignedaddress to the UE_A 10. In addition, in a case that the SMF_A 230assigns the IPv4 address, and/or the IPv6 address, and/or the IPv6prefix using the DHCPv4 or the DHCPv6 or Stateless AddressAutoconfiguration (SLAAC), the SMF_A 230 may assign the address afterthe PDU session establishment procedure or may transmit the assignedaddress to the UE_A 10. Note that the address allocation performed bySMF_A 230 is not limited to these.

Furthermore, based on the completion of address assignment of an addressto be assigned to the UE_A 10, the SMF_A 230 may include the assignedaddress in the PDU session establishment accept message and transmit thePDU session establishment accept message to the UE_A 10, or transmit thePDU session establishment accept message to the UE_A 10 after thecompletion of the PDU session establishment procedure.

The SMF_A 230 transmits the PDU session establishment accept message tothe UE_A 10 via the AMF_A 240, based on the reception of the PDU sessionestablishment request message, and/or the selection of the UPF_A 235,and/or the reception of the session establishment response message,and/or the completion of the address assignment of the address to beassigned to the UE_A 10 (S1110).

Specifically, the SMF_A 230 transmits the PDU session establishmentaccept message to the AMF_A 240 by using the N11 interface. The AMF_A240 receives the PDU session establishment accept message and transmitsthe PDU session establishment accept message to the UE_A 10 by using theN1 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment accept message may be a PDN connectivity acceptmessage. Furthermore, the PDU session establishment accept message maybe a NAS message transmitted and/or received on the N11 interface andthe N1 interface. The PDU session establishment accept message is notlimited to the PDU session establishment accept message described above,and only needs to be a message indicating the acceptance of theestablishment of the PDU session.

The UE_A 10 receives the PDU session establishment accept message fromthe SMF_A 230. By receiving the PDU session establishment acceptmessage, the UE_A 10 recognizes the contents of various types ofidentification information included in the PDU session establishmentaccept message.

Then, based on the completion of the reception of the PDU sessionestablishment accept message, the UE_A 10 transmits the PDU sessionestablishment complete message to the SMF_A 230 via the AMF_A 240(S1114). Furthermore, the SMF_A 230 receives the PDU sessionestablishment complete message, and performs the second conditiondetermination.

Specifically, the UE_A 10 transmits the PDU session establishmentcomplete message to the AMF_A 240 by using the N1 interface. The AMF_A240 receives the PDU session establishment complete message, andtransmits the PDU session establishment complete message to the SMF_A230 by using the N11 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment complete message may be a PDN Connectivitycomplete message, or may be an Activate default EPS bearer contextaccept message. Furthermore, the PDU session establishment completemessage may be a NAS message transmitted and/or received on the N1interface and the N11 interface. The PDU session establishment completemessage only needs to be a response message to the PDU sessionestablishment accept message. However, the PDU session establishmentcomplete message is not limited to this, and only needs to be a messageindicating that the PDU session establishment procedure is completed.

The second condition determination is intended to determine, by theSMF_A 230, the type of the message on the N4 interface that istransmitted and/or received. In a case that the second conditiondetermination is true, then processing #3 in the core network may beinitiated (S1115). Here, the processing #3 in the core network mayinclude transmission and/or reception of the Session Modificationrequest message and/or transmission and/or reception of the SessionModification response message. The SMF_A 230 transmits the sessionmodification request message to the UPF_A 235, and further receives thesession modification accept message transmitted from the UPF_A 235,having received the session establishment request message. Additionally,in a case that the second condition determination is false, the SMF_A230 performs the processing #2 in the core network. In other words, theSMF_A transmits the session establishment request message to the UPF_A235, and further receives the session modification accept messagetransmitted from the UPF_A 235, having received the sessionestablishment request message.

Each apparatus completes the procedure of (A) in the present procedure,based on the transmission and/or reception of the PDU sessionestablishment complete message, and/or the transmission and/or receptionof the session modification response message, and/or the transmissionand/or reception of the session establishment response message, and/orthe transmission and/or reception of Router Advertisement (RA).

Now, steps performed in a case that the third condition determination isfalse, in other words, each step of the procedure of (B) in the presentprocedure will be described. The SMF_A 230 transmits the PDU sessionestablishment reject message to the UE_A 10 via the AMF_A 240 (S1122),and initiates the procedure of (B) in the present procedure.

Specifically, the SMF_A 230 transmits the PDU session establishmentreject message to the AMF_A 240 by using the N11 interface, and theAMF_A 240 receives the PDU session establishment request message andtransmits the PDU session establishment reject message to the UE_A 10 byusing the N1 interface.

Note that in a case that the PDU session is PDN connection, the PDUsession establishment reject message may be a PDN Connectivity rejectmessage. Furthermore, the PDU session establishment reject message maybe a NAS message transmitted and/or received on the N11 interface andthe N1 interface. The PDU session establishment reject message is notlimited to the PDU session establishment reject message described above,and only needs to be a message indicating that the PDU sessionestablishment has been rejected.

Here, the SMF_A 230 may include, in the PDU session establishment rejectmessage, one or more pieces of identification information from the 11thto 18th pieces of identification information, or may indicate that therequest of the UE_A 10 has been rejected by including these pieces ofidentification information. Note that two or more of these pieces ofidentification information may be configured as one or more pieces ofidentification information.

Furthermore, the SMF_A 230 may transmit the 11th piece of identificationinformation and/or the 12th piece of identification information and/orthe 13th piece of identification information and/or the 14th piece ofidentification information and/or the 15th piece of identificationinformation and/or the 16th piece of identification information and/orthe 17th piece of identification information; and/or the 18th piece ofidentification information included in the PDU session establishmentreject message to indicate that the request to establish a PDU sessionbelonging to the network slice has been rejected, or may indicatenetwork slices to which the PDU session is not allowed to belong.

More particularly, the SMF_A 230 may transmit the 18th piece ofidentification information and the 12th piece of identificationinformation in association with each other to indicate, in a PDU sessionestablished for the DN identified by the 12th piece of identificationinformation, that the request to establish a PDU session belonging tothe network slice has been rejected, or indicate the network slices towhich the PDU session is not allowed to belong.

Furthermore, the SMF_A 230 may transmit the 18th piece of identificationinformation included in the PDU session establishment reject message toindicate that the request to establish a PDU session belonging to thenetwork slice has been rejected in the registration area and/or trackingarea to which the UE_A 10 currently belongs or to indicate the networkslices not allowed to belong to the PDU session.

Furthermore, the SMF_A 230 may transmit the 18th piece of identificationinformation included in the PDU session establishment reject message toindicate that the request to establish a PDU session belonging to thenetwork slice has been rejected in the access network to which the UE_A10 is currently connected or to indicate the network slices to which thePDU session is not allowed to belong.

Furthermore, the SMF_A 230 may indicate the value of the first timer bytransmitting the 11th piece of identification information and/or the14th piece of identification information included in the PDU sessionestablishment reject message, and may indicate whether the sameprocedure as the present procedure is to be performed again after thecompletion of the present procedure.

Furthermore, the SMF_A 230 may transmit two or more pieces ofidentification information from the 11th to 18th pieces ofidentification information in combination to make a request for acombination of the above-described matters. Note that the mattersindicated by the SMF_A 230 transmitting the identification informationmay not be limited thereto.

Note that the SMF_A 230 may determine which piece of identificationinformation from the 11th to 18th pieces of identification informationis to be included in the PDU session establishment reject message, basedon the received identification information, and/or the capabilityinformation of the network, and/or the policy such as the operatorpolicy, and/or the state of the network.

Furthermore, the 12th piece of identification information may beinformation indicating the same DNN as the DNN indicated by the secondpiece of identification information. Furthermore, the 13th piece ofidentification information may be information indicating the same PDUsession ID as the PDU session ID indicated by the third piece ofidentification information. Furthermore, the 18th piece ofidentification information may be information transmitted in a case thatthe first piece of identification information is received and/or in acase that the network slice indicated by the first piece ofidentification information is not granted by the network. Note that,determination performed by the SMF_A 230 as to which piece ofidentification information is to be included in the PDU sessionestablishment reject message is not limited to the determinationdescribed above.

As described above, the core network_B 190 transmits the PDU sessionreject message to notify the UE_A 10 of congestion control to be appliedto the UE_A 10. Note that the core network_B 190 may notify the UE_A 10that the congestion control is applied to the UE_A 10 and/or that thecongestion control is indicated to be performed on the UE_A 10, and/orinformation for identifying the type of the congestion control to apply,and/or information for identifying the target of the congestion control,such as the DNN and/or S-NSSAI corresponding to the congestion controlto apply, and/or the value of the timer associated with the congestioncontrol to apply.

Here, each of the above-described pieces of information may beinformation identified by one or more piece of identificationinformation from the 11th to 18th pieces of identification information.

The PDU session establishment reject message received by the UE_A 10from the SMF_A 230 may include one or more pieces of identificationinformation from the 11th to 18th pieces of identification information.

Then, the UE_A 10 performs the fourth step of processing based on thereception of the PDU session establishment reject message (S1124).Alternatively, the UE_A 10 may perform the fourth step of processingbased on the completion of the present procedure.

A first example of the fourth step of processing will be describedbelow.

Here, the fourth step of processing may be processing in which the UE_A10 recognizes the matter indicated by the SMF_A 230. Furthermore, thefourth step of processing may be processing in which the UE_A 10 storesthe received identification information as a context, or processing inwhich the received identification information is transferred to a higherlayer and/or a lower layer. Furthermore, the fourth step of processingmay be processing in which the UE_A 10 recognizes that the request forthe present procedure has been rejected.

Furthermore, in a case that the UE_A 10 receives the 14th piece ofidentification information and the 11th piece of identificationinformation, the fourth step of processing may be processing in whichthe UE_A 10 configures a first timer value by using the value indicatedby the 14th piece of identification information, or processing forinitiating the first timer with the timer value configured. Furthermore,in a case that the UE_10 receives the 11th piece of identificationinformation, the fourth step of processing may be processing forperforming one or more behaviors from the first to 11th behaviors.

Furthermore, in a case that the UE_A 10 receives the 18th piece ofidentification information and the 11th piece of identificationinformation, the fourth step of processing may be processing in whichthe UE_A 10 performs 12th behavior based on information for identifyingthe NW slice included in the 18th piece of identification information,the network slice association rule included in the 18th piece ofidentification information, or the network slice association ruleinitially held and configured by the UE_A 10.

Furthermore, in a case that the UE_A 10 receives the multiple 14thpieces of identification information and the 11th piece ofidentification information, the fourth step of processing may beprocessing in which the UE_A 10 performs 13th behavior based on themultiple first timers included in the 14th pieces of identificationinformation and the priority management rule for the back-off timer heldby the UE_A 10.

Furthermore, in a case that the UE_A 10 receives the multiple 14th pieceof identification information and the 11th piece of identificationinformation, the fourth step of processing may be processing in whichthe UE_A 10 performs 14th behavior based on the multiple first timersincluded in the 14th pieces of identification information.

Here, the 12th to 15th behaviors may be congestion control initiated andperformed by the UE_A 10 based on rules and/or policies inside the UE_A10. Specifically, for example, the UE_A 10 may include, in a storageunit and/or a controller inside the UE_A 10, a policy (UE policy) and/ora rule, a management function for the policy and/or rule, a policyenforcer operating the UE_A 10 based on the policy and/or rule, one ormore applications, and a session management instance (session manager)for managing one or more PDU sessions that the UE_A 10 establishes orattempts to establish based on a request from each application. Byperforming any of the 12th to 15th behaviors as the fourth step ofprocessing based on the above, the congestion control initiated by theUE_A 10 may be implemented. Here, the policy and/or rule may include oneor more of the network slice association rule and/or the prioritymanagement rule for the back-off timer, and/or a Network Slice SelectionPolicy (NSSP), which may be initially configured in the UE_A 10 orreceived from the network. Here, the policy enforcer may be an NSSPenforcer. Additionally, here, the application may be a protocol in theapplication layer, and an PDU session may be established or an attemptmay be made to establish a PDU session, based on a request from theprotocol in the application layer. Additionally, here, the sessionmanagement instance may be a software element dynamically generated inunits of PDU sessions. Additionally, here, as internal processing by theUE_A 10, S-NSSAI may be grouped or processing based on the grouping ofthe S-NSSAI may be performed. Note that the present invention is notlimited to the internal configuration and processing of the UE_A 10described above, and each element may be implemented in software or maybe performed as software processing within the UE_A 10.

Furthermore, the UE_A 10 may switch to the EPS, in the fourth step ofprocessing or based on the completion of the fourth step of processing,and may initiate position registration in the EPS based on the DCN IDincluded in the 18th piece of identification information. Note thatswitching to the EPS by the UE_A 10 may be based on a handoverprocedure, or may be RAT switching initiated by the UE_A 10.Additionally, in a case that the UE_A 10 receives the 18th piece ofidentification information including the DCN ID, the UE_A 10 may performswitching to EPS during the fourth step of processing or after thecompletion of the fourth step of processing.

Furthermore, the fourth step of processing may be processing in whichthe UE_A 10 initiates the present procedure again after a certain periodof time, or processing in which the UE_A 10 request transitions to alimited or restricted state.

Note that, in response to the completion of the fourth step ofprocessing, the UE_A 10 may transition to the first state.

Now, a second example of the fourth step of processing will bedescribed.

Here, the fourth step of processing may be processing in which the UE_A10 recognizes the matter indicated by the SMF_A 230. Furthermore, thefourth step of processing may be processing in which the UE_A 10 storesthe received identification information as a context, or processing inwhich the received identification information is transferred to a higherlayer and/or a lower layer.

Furthermore, in the fourth step of processing, processing foridentifying application of the congestion control may be performed basedon one or more piece of identification information from the 11th to 18thpieces of identification information.

Furthermore, in the fourth step of processing, the following may beperformed: processing for identifying which of the first to fourth typesof congestion control is to be applied based on one or more pieces ofidentification information from the 11th to 18th pieces ofidentification information, and processing for identifying the DNNand/or S-NSSAI associated with the congestion control to apply. Morespecifically, the present processing may be processing described in 15thbehavior.

Furthermore, in the fourth step of processing, the value configured forthe first timer indicated by the 14th piece of identificationinformation associated with the congestion control to apply may beidentified and configured based on one or more pieces of identificationinformation from the 11th to 18th pieces of identification information,and counting of the first timer may be initiated. More specifically, thepresent processing may be the processing described in eighth behavior.

Furthermore, in the fourth step of processing, one or more of the firstto seventh behaviors may be performed in response to the initiation orcompletion of any of the steps of processing described above.

Furthermore, in the fourth step of processing, one or more of ninth to15th behaviors may be performed in response to the initiation orcompletion of any of the steps of processing described above.

Note that, in response to the completion of the fourth step ofprocessing, the UE_A 10 may transition to the first state.

While processing contents have been described with respect to the fourthstep of processing using the first example and the second example, thepresent embodiment need not be limited to these steps of processing ofthe fourth step of processing. For example, the fourth step ofprocessing may be a combination of some of the multiple steps ofdetailed processing described in the first example and some of themultiple steps of detailed processing described in the second example.

Furthermore, the UE_A 10 may recognize that the request of the UE_A 10has been rejected by receiving the PDU session establishment rejectmessage or not receiving the PDU session establishment accept message.Each apparatus completes the procedure of (B) in the present procedure,based on transmission and/or reception of the PDU session establishmentreject message.

Each apparatus completes the present procedure, based on completion ofthe procedure of (A) or (B) in the present procedure. Note that eachapparatus may transition, based on the completion of the procedure of(A) in the present procedure, to a state in which the PDU session isestablished, may recognize, based on the completion of the procedure of(B) in the present procedure, that the present procedure has beenrejected, or may transition to a state in which the PDU session is notestablished or to the first state.

Furthermore, each apparatus may perform processing based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure. In other words,the UE_A 10 may perform the fourth step of processing based on thecompletion of the present procedure, or may transition to the firststate after completion of the fourth step of processing.

Additionally, the third condition determination may be performed basedon the identification information included in the PDU sessionestablishment request message, and/or the subscriber information, and/orthe operator policy. For example, the third condition determination maybe true in a case that the network grants the request of the UE_A 10. Inaddition, the third condition determination may be false in a case thatthe network does not grant the request of the UE_A 10. Furthermore, in acase that the network corresponding to the connection destination of theUE_A 10 and/or the apparatus in the network supports the functionrequested by the UE_A 10, the third condition determination may be true,and in a case that the function is not supported, the third conditiondetermination may be false. Furthermore, the third conditiondetermination may be true in a case that the network is determined to becongested, and may be false in a case that the network is determined notto be congested. Note that conditions for determining whether the thirdcondition determination is true or false need not be limited to theabove-described conditions.

The second condition determination may be performed based on whether thesession on the N4 interface for the PDU session has been established.For example, in a case that the session on the N4 interface for the PDUsession has been established, the second condition determination may betrue, and in a case that the session on the N4 interface for the PDUsession is not established, the second condition determination may befalse. Conditions for determining true or false of the second conditiondetermination need not be limited to the above-described conditions.

The 11th condition determination may be performed based on theidentification information included in the PDU session establishmentrequest message, and/or the subscriber information, and/or the operatorpolicy. For example, the 11th condition determination may be true in acase that the network allows authentication and/or authorization by theDN_A 5 to be performed during the present procedure. Additionally, the11 condition determination may be false in a case that the network doesnot allow authentication and/or authorization by the DN_A 5 to beperformed during the present procedure. Furthermore, in a case that thenetwork corresponding to the connection destination of the UE_A 10and/or the apparatus in the network supports the performance of theauthentication and/or authorization by the DN_A 5 during the presentprocedure, the 11th condition determination may be true, and in a casethat the performance during the present procedure is not supported, the11th condition determination may be false. Furthermore, the 11thcondition determination may be true in a case that 61st piece ofidentification information is received, and may be false in a case thatthe 61st piece of identification information is not received. In otherwords, the 11th condition determination may be true in a case thatinformation such as an SM PDU DN Request Container and/or a containerincluding multiple pieces of information is received, and the 11thcondition information may be false in a case that such information isnot received. Note that conditions for determining whether the 11thcondition determination is true or false may not be limited to theabove-described conditions.

The transmission and reception of the PDU session reject message in theabove-described procedure allow the core network_B 190 to notify theUE_A 10 of the congestion control to apply, and allow the UE_A 10 toapply the congestion control indicated by the core network_B 190. Notethat the core network_B 190 and the UE_A 10 may apply multiple types ofcongestion control by performing the procedures and processes describedin the present procedure multiple times. Note that the congestioncontrol to apply may vary in terms of different types of congestioncontrol, and/or correspondence to different DNNs, and/or correspondenceto different pieces of S-NNSAI, and/or correspondence to differentcombinations of the DNN and S-NSSAI.

1.3.3. Overview of Network Initiated Session Management Procedure

Now, an overview of the network-initiated session management procedurewill be provided. Hereinafter, the network-initiated session managementprocedure is also referred to as the present procedure. The presentprocedure is a procedure for session management initiated and performedon an established PDU session by the network. Note that the present,procedure may be performed at any timing after the registrationprocedure and/or the PDU session establishment procedure described aboveis completed to cause each apparatus to transition to the first state.Additionally, each apparatus may transmit and/or receive a messageincluding identification information for stopping or changing thecongestion control during the present procedure, or may initiate thebehavior based on new congestion control indicated by the network basedon the completion of the present procedure.

Alternatively, the UE_A 10 may stop the application of the congestioncontrol identified based on control information transmitted and/orreceived in accordance with the present procedure. In other words, byinitiating the present procedure and further transmitting the controlmessage and control information of the present procedure to the UE_A 10,the core network_B 190 can notify the UE_A 10 to stop the application ofthe congestion control that can be identified by using the controlinformation.

Note that the present procedure may be a network-initiated PDU sessionmodification procedure, and/or a network-initiated PDU session releaseprocedure, or the like, or a network-initiated session managementprocedure not limited to the above-described procedures may beperformed. Each apparatus may transmit and/or receive the PDU sessionmodification message in the network-initiated PDU session modificationprocedure, or may transmit and/or receive the PDU session releasemessage in the network-initiated PDU session release procedure.

1.3.3.1. Example of First Network-Initiated Session Management Procedure

An example of a network-initiated session management procedure will bedescribed by using FIG. 12. In the present section, the presentprocedure refers to a network-initiated session management procedure.Each step of the present procedure will be described below.

As described above, based on the completion of the registrationprocedure and/or the PDU session establishment procedure (S1200), theUE_A 10 and each apparatus in the core network_B 190 transition to thefirst state and initiate the network-initiated session managementprocedure at any timing. Here, the apparatus in the core network_B 190that initiates the present procedure may be the SMF_A and/or the AMF_A,and the UE_A may transmit and/or receive the message in the presentprocedure via the AMF_A and/or the access network_B.

Specifically, the apparatus in the core network_B 190 transmits thenetwork-initiated session management request message to the UE_A(S1202). Here, the apparatus in the core network_B 190 may include 21stpiece of identification information in the network-initiated sessionmanagement request message, or may indicate the request of the corenetwork_B 190 by including the identification information.

Then, the UE_A receives the network-initiated session management requestmessage and transmits a network-initiated session management completemessage (S1204). Furthermore, based on the 21st piece of identificationinformation received from the core network_B 190, the UE_A may performthe fifth processing (S1206) to complete the present procedure. The UE_A10 may perform the fifth processing based on the completion of thepresent procedure.

An example of the fifth processing will be described below.

Here, the fifth processing may be processing in which the UE_A 10recognizes the matter indicated by the core network_B 190, or recognizesthe request of the core network_B 190. Furthermore, the fifth processingmay be processing in which the UE_A 10 stores the receivedidentification information as a context, or processing in which thereceived identification information is transferred to a higher layerand/or a lower layer.

The message transmitted and/or received in the network-initiated sessionmanagement request may be, although not limited to, a PDU sessionmodification command (PDU SESSION MODIFICATION COMMAND) or a PDU sessionrelease command (PDU SESSION RELEASE COMMAND).

Note that the UE_A 10 may perform congestion control identificationprocessing applied by the UE_A 10 based on the received 21st piece ofidentification information in the fifth processing, Here, the congestioncontrol identification processing may be the 17th behavior.

Furthermore, in a case that the UE_A 10 receives the 21st identificationinformation, the fifth processing may be the 16th behavior.Specifically, the processing may be, for example, processing involvingstopping one or multiple timers run based on the above-described fourthstep of processing.

In other words, the UE_A 10 receives the 21st identificationinformation, then performs the 17th behavior to identify the congestioncontrol to be stopped or changed in accordance with an indication fromthe network, and subsequently performs the 16th behavior to stop orchange the identified congestion control.

Furthermore, each apparatus may perform processing based onidentification information transmitted and/or received in the presentprocedure, based on completion of the present procedure. In other words,the UE_A 10 may perform the fifth processing based on the completion ofthe present procedure, or may complete the present procedure after thecompletion of the fifth processing.

In the above-described procedure, the network-initiated sessionmanagement request message is transmitted and/or received to allow thecore network_B 190 to indicate to the UE_A 10 to stop or change thecongestion control already applied to the UE_A 10. Furthermore, the UE_A10 may stop or change the congestion control applied by the UE_A 10,based on the network-initiated session management request message. Here,in a case that the UE_A 10 has one or more congestion control in effect,the UE_A 10 may identify the congestion control to be stopped or changedbased on the reception of the identification information included in thenetwork-initiated session management request message from the corenetwork_B 190. Note that the congestion control to apply may vary interms of different types of congestion control, and/or correspondence todifferent DNNs, and/or correspondence to different pieces of S-NNSAI,and/or correspondence to different combinations of the DNN and S-NSSAI.

1.3.3.2 Example of Second Network-Initiated Session Management Procedure

In the example of the first network-initiated session managementprocedure described in section 1.3.3.1, an example in which thecongestion control is stopped during the procedure regardless ofwhichever congestion control of the first to fourth types of congestioncontrol is applied to the UE_A 10 is described.

The present invention is not limited to the example, and the proceduredescribed in the example of the first network-initiated sessionmanagement procedure described in section 1.3.3.1 may be a procedureperformed in accordance with the congestion control. For example, of oneor multiple types of congestion control applied by the UE_A 10, theprocedure may be performed on the congestion control classified into thefirst, third, or fourth type of congestion control.

In other words, the UE_A 10 may perform the fifth processing to stop thecongestion control corresponding to the first, third, and fourth typesof congestion control.

In a case of receiving the network-initiated session management requestmessage for the second type of congestion control while performingcounting of the back-off timer associated with the second type ofcongestion control, the UE_A 10 may respond to the core network_B 190without stopping the back-off timer associated with the second type ofcongestion control.

In other words, in a case of receiving the network-initiated sessionmanagement request message for S-NSSAI #A, which is congested, and anyDNN while performing the counting of the back-off timer associated withthe S-NSSAI #A, the UE_A 10 may respond to the core network_B 190without stopping the back-off timer associated with the S-NSSAI #A.

Thus, for the second type of congestion control, in receiving thenetwork-initiated session management request message, the UE_A 10 maytransmit, to the core network_B 190, the response message for thenetwork-initiated session management request message, but may continuethe congestion control. Accordingly, the transmission of theUE-initiated session management request message, restricted by thesecond type of congestion control, may continue to be inhibited.

Here, as described above, the network-initiated session managementrequest message in the present embodiment may be the PDU sessionmodification command (PDU SESSION MODIFICATION COMMAND) message in thenetwork-initiated PDU session modification procedure or the PDU sessionrelease command (PDU SESSION RELEASE COMMAND) message in thenetwork-initiated PDU session release procedure.

Moreover, as described above, the network-initiated session managementcomplete message responsive to the PDU session modification commandmessage in the present embodiment may be a PDU session modificationcomplete message (PDU SESSION MODIFICATION COMPLETE), and thenetwork-initiated session management complete message responsive to thePDU session release command message in the present embodiment may be aPDU session release complete message (PDU SESSION RELEASE COMPLETE).Additionally, in a case that the network-initiated session managementrequest message is the PDU session modification command and/or the PDUsession release message, the UE_A 10 and the core network_B 190 may beconfigured to perform, in addition to the above-described processing,further detailed processing described below.

For example, in a case that the core network_B 190 transmits thenetwork-initiated session management request message includinginformation indicating a Reactivation Required, the core network_B 190may perform processing as follows. Note that the information indicatingthe Reactivation Required is information indicating that activation isrequested, and particular examples may be a 5G session management. causevalue #39 (5G SM Cause #39).

Hereinafter, an example of the first step of processing and procedureperformed in a case that information indicating the reactivationrequired is received will be described.

In a case that the UE_A 10 receives a network-initiated sessionmanagement request message including information indicating theReactivation Required, then instead of initiating the UE-initiated PDUsession establishment procedure immediately after completion of thenetwork-initiated session management procedure, the UE_A 10 initiatesthe UE-initiated PDU session establishment procedure again after thecongestion control is released. Here, the UE-initiated PDU sessionestablishment procedure may be a UE-initiated PDU session establishmentprocedure for the PDU session type, the SSC mode, and the DNN andS-NSSAI provided in the UE-initiated PDU establishment procedure in acase that a PDU session to be modified or released is established.

Note that the initiation after the release of the congestion control maymean execution after the timer associated with the second type ofcongestion control Expires. In other words, the initiation after therelease of the congestion control may mean execution after completion ofthe counting of the timer associated with the second type of congestioncontrol and/or after the timer value associated with the second type ofcongestion control becomes zero.

Furthermore, the UE_A 10 may include the following supplementalinformation in the network-initiated session management completemessage.

The supplemental information may be information indicating executionafter expiry of the timer and/or information indicating the remainingtimer value. Here, the timer may be a timer associated with the secondtype of congestion control. The execution after expiry of the timer maymean that the procedure is performed after the timer Expires. In otherwords, the execution after expiry of the timer may mean execution aftercompletion of the counting of the timer associated with the second typeof congestion control and/or after the timer value associated with thesecond type of congestion control becomes zero.

Note that the core network_B 190 may receive the network-initiatedsession management complete message including the supplementalinformation and recognize the remaining timer value. Furthermore, thecore network_B 190 may recognize that the UE-initiated PDU sessionestablishment procedure is initiated after the time corresponding to thevalue indicated by the remaining timer elapses.

Here, the remaining timer recognized by the core network_B 190 maycorrespond to a value indicated by the received supplementalinformation, or a value obtained by considering the offset between thetime of the transmission, by the UE_A 10, of the network-initiatedsession management complete message and the time of the reception, bythe core network_B 190, of the network-initiated session managementcomplete message, with respect to the value indicated by the receivedsupplemental information.

In addition, the present invention is not limited to the example of thefirst step of processing and procedure for a case of reception of theinformation indicating the reactivation required, but an example of thesecond step of processing and procedure for a case of reception of theinformation indicating the reactivation required may be performed asdescribed below.

As described above, for the second type of congestion control, inreceiving the network-initiated session management request message, theUE_A 10 may transmit, to the core network_B 190, a response message forthe network-initiated session management request message, but maycontinue the congestion control. Thus, the configuration may be suchthat, while the transmission of the UE-initiated session managementrequest message, restricted by the second type of congestion control,continues to be inhibited, the UE_A 10 and/or the core network_B 190 isonly allowed to initiate the UE-initiated PDU session establishmentprocedure again.

In other words, in a case of receiving the network-initiated sessionmanagement request message including information indicating theReactivation Required, then the UE_A 10 completes the network-initiatednetwork-initiated session management procedure and then initiates theUE-initiated PDU session establishment procedure again. Here, theUE-initiated PDU session establishment procedure may be a UE-initiatedPDU session establishment procedure for the PDU session type, the SSCmode, and the DNN and S-NSSAI provided in the UE-initiated PDUestablishment procedure in a case that a PDU session to be modified orreleased is established.

Note that, while the congestion control remains in effect, the UE_A, 10and the core network B190 may perform and complete the procedureaccepted as an exception but that the UE_A 10 may be inhibited frominitiating other UE-initiated session management procedures inhibited bythe second type of congestion control.

In addition, the present invention is not limited to the examples of thefirst and second steps of processing and procedures for a case ofreception of the information indicating the reactivation required, butan example of the third step of processing and procedure for a case ofreception of the information indicating the reactivation required may beperformed as described below.

As described above, for the second type of congestion control, inreceiving the network-initiated session management request message, theUE_A 10 transmits, to the core network_B 190, a response message for thenetwork-initiated session management request message. Furthermore, in acase that the UE_A 10 receives the network-initiated session managementrequest message including information indicating the ReactivationRequired, the UE_A 10 may stop the application of the second type ofcongestion control.

In other words, the UE_A 10 may continue the congestion control in acase that the network-initiated session management request message doesnot include information indicating a Reactivation Required. In thiscase, the transmission of the UE-initiated session management requestmessage, restricted by the second type of congestion control, maycontinue to be inhibited.

Accordingly, in a case of receiving the network-initiated sessionmanagement request message including information indicating theReactivation Required, then the UE_A 10 completes the network-initiatednetwork-initiated session management procedure and then initiates theUE-initiated PDU session establishment procedure again. Here, theUE-initiated PDU session establishment procedure may be a UE-initiatedPDU session establishment procedure for the PDU session type, the SSCmode, and the DNN and S-NSSAI provided in the UE-initiated PDUestablishment procedure in a case that a PDU session to be modified orreleased is established.

In addition, the present invention is not limited to the examples of thefirst, second, and third steps of processing and procedures for a caseof reception of the information indicating the reactivation required,but the information indicating the reactivation required may beprevented from being transmitted by the core network_B 190 as describedbelow.

More specifically, the core network_B 190 may be configured to, in acase of transmitting the network-initiated session management requestmessage to the UE_A 10 with the congestion control in effect, to inhibitinformation indicating the Reactivation Required from being included inthe network-initiated session management request message.

Alternatively, the core network_B 190 may be configured to, in a case oftransmitting the network-initiated session management request message tothe UE_A 10 with the second type of congestion control in effect, toinhibit information indicating the Reactivation Required from beingincluded in the network-initiated session management request message.

Although the processing and procedure performed by the UE_A 10 and thecore network B190 have been described above, the processing by the corenetwork_B 190 described in the present section may be processingperformed by a control apparatus such as the SMF_A 230 and/or the AMF_A240, which are apparatuses within the core network_B 190. Thus, the corenetwork B190 transmitting and/or receiving control messages maycorrespond to a control apparatus such as the SMF_A 230 and/or AMF_A240, which is an apparatus in the core network_B 190, transmittingand/or receiving the control messages.

Furthermore, although not limited to this section, in expressions usedin the description of the present embodiment, releasing the applicationof congestion control or stopping congestion control may includeprocessing for stopping the back-off timer associated with congestioncontrol, and continuing the application of congestion control orcontinuing congestion control may include continuing to count theback-off timer associated with congestion control.

Additionally, in the description of the examples of the first, second,and third steps of processing and procedures for a case that receivingthe information indicating the reactivation required described in thepresent section, in the network-initiated session management requestmessage and/or the network-initiated session management procedure, theUE_A 10 is for S-NSSAI #A being congested, and any DNN.

In other words, S-NSSAI #A, which is congested, and any DNN may beS-NSSAI #A and any DNN associated with the PDU session for which thenetwork-initiated session management request message and/ornetwork-initiated session management procedure are intended in thepresent section.

Note that the UE_A 10 and the core network_B 190 may perform an anchorrelocation procedure in an SSC mode 2 including the procedure in thepresent section, and switch to the anchor of a PDU session or to a PDUsession with a different anchor to continue communication. Here, theanchor relocation procedure in the SSC mode 2 is a procedure initiatedby the core network_B 190, and the procedure involved in transmission ofthe PDU session release command performed in the procedure may be anyprocedure described in this section.

Additionally, the UE_A 10 and the core network_B 190 may perform ananchor relocation procedure in an SSC mode 3 including the procedure inthe present section, and switch to the anchor of a PDU session or a PDUsession with a different anchor to continue communication. Here, theanchor relocation procedure in the SSC mode 3 is a procedure initiatedby the core network_B 190, and the procedure involved in transmission ofthe PDU session modification command performed in the procedure may beany procedure described in this section.

Now, processing will be described that is performed in a case that, withcongestion control in effect, the UE makes movement involving a changeof the PLMN.

Here, processing will be described in which the UE_A 10 changes thePLMN, particularly while the first type of congestion control is ineffect. Here, the first type of congestion control and the processingrestricted in a case that the first type of congestion control isapplied may be as described above.

Again, the first type of congestion control may be a DNN-basedcongestion control. For example, the first type of congestion controlmay be congestion control applied to the UE_A 10 by the NW based on amessage indicating rejection of the UE-initiated session managementrequest in a case that the NW receives, from the UE_A 10, theUE-initiated session management request with DNN #A and that the NWdetects congestion on a specific DNN, for example, DNN #A. In this case,when the first type of congestion control is applied, the UE_A 10initiates counting the back-off timer for the first type of congestioncontrol received from the NW and is configured not to transmit theUE-initiated session management request with the DNN #A until theback-off timer expires. Note that “with DNN” may indicate to include DNNinformation in the UE-initiated session management request such as thePDU session establishment request message.

Here, for description, the first type of congestion control as describedabove is expressed as “the first type of congestion control for aspecific DNN.”

Additionally, in the first type of congestion control, on the initiativeof the NW, the default DNN may be selected as a congestion controltarget even in a case that no DNN information is included in theUE-initiated session management request. In other words, the first typeof congestion control may be configured to: receive a UE-initiatedsession management request that does not use DNN information from theUE_A 10 and detects congestion to the default DNN at the NW: Based onthe message rejecting the UE-initiated session management request, theNW can be congestion control for application to the UE_A 10. In thiscase, the application of the first type of congestion control may beconfigured such that the UE_A 10 initiates counting the back-off timercorresponding to the first type of congestion control received from theNW and refrains from transmitting the UE-initiated session managementrequest without DNN until the back-off timer expires. Note that notusing the DNN may be to include no DNN information in the UE-initiatedsession management request such as the PDU session establishment requestmessage.

Here, for description, the first type of congestion control for thedefault DNN is applied based on the UE-initiated session managementrequest without DNN information, and is thus expressed as “congestioncontrol for No DNN” to distinguish from the first type of congestioncontrol for a specific DNN. Furthermore, the UE-initiated sessionmanagement request such as the PDU session establishment request messagewithout DNN is expressed as the UE-initiated session management requestusing No DNN. For example, the PDU session establishment request messageusing No DNN is the PDU session establishment request message withoutDNN.

Upon a PLMN change, in a case that the UE_A 10 has the back-off timerassociated with the first type of congestion control for a specific DNNrunning, or the back-off timer associated with the first type ofcongestion control for the specific DNN is deactivated, then the UE_A 10is configured to be able to transmit, in the new PLMN, the PDU sessionestablishment request message with the specific DNN. Accordingly, basedon this configuration, the UE_10 may transmit the PDU sessionestablishment request message with the specific DNN.

Here, the UE_A 10 may not stop the running back-off timer and keep theback-off timer running until the timer expires. Alternatively, the UE_A10 may keep the deactivated back-off timer in a deactivated state.

Thus, the first type of congestion control for the specific DNN may beassociated with the PLMN.

For example, in a case that the first type of congestion control for thespecific DNN is applied, the UE initiates counting with the back-offtimer associated with the PLMN and the specific DNN. In a case that theback-off timer is not zero or deactivated, the UE does not perform, inthe PLMN associated with the back-off timer, establishment of a PDUsession using the specific DNN associated with the back-off timer. Inaddition, in a case that the back-off timer is deactivated, the UE doesnot perform, in the PLMN associated with the back-off timer,establishment of a PDU session using the specific DNN associated withthe back-off timer until the terminal is powered off or the USIM isremoved. Additionally, in a case that the back-off timer is zero,establishment of a PDU session with the specific DNN associated with theback-off timer may be performed in the PLMN associated with the back-offtimer.

In other words, upon a PLMN change, in a case that the UE_A 10 has theback-off timer associated with the first type of congestion control fora specific DNN and old PLMN running, or the back-off timer associatedwith the first type of congestion control for the specific DNN and theold PLMN is deactivated, and in a case that the back-off timerassociated with the first type of congestion control for the specificDNN and new PLMN is not running, and the back-off timer associated withthe first type of congestion control for the specific DNN and the newPLMN is not deactivated, then the UE_A 10 is configured to be able totransmit, in the new PLMN, the PDU session establishment request messagewith the specific DNN. Furthermore, based on this configuration, the UE_10 may transmit the PDU session establishment request message with thespecific DNN.

Upon a PLMN change, in a case that the UE_A 10 has the back-off timerassociated with the first type of congestion control for No DNN running,or the back-off timer associated with the first type of congestioncontrol for No DNN is deactivated, then the UE_A 10 is configured to beable to transmit, in the new PLMN, the PDU session establishment requestmessage without DNN. Accordingly, based on this configuration, the UE_10 can transmit the PDU session establishment request message with thespecific DNN.

Here, the UE_A 10 does not stop the back-off timer being counted by theUE_A 10 and may continue counting until the timer expires.Alternatively, the UE_A 10 may continue to hold the deactivated back-offtimer in a deactivated state.

As described above, the first type of congestion control for No DNN maybe associated with the PLMN. In other words, upon a PLMN change, in acase that the UE_A 10 has the back-off timer for the first type ofcongestion control for No DNN associated with old PLMN running, or theback-off tinier for the first type of congestion control for No DNNassociated with the old PLMN is deactivated, and in a case that theback-off timer for the first type of congestion control for No DNNassociated with new PLMN is not running, and the back-off timer for thefirst type of congestion control for No DNN associated with the PLMN isnot deactivated, then the UE_A 10 is configured to be able to transmit,in the new PLMN, the PDU session establishment request message withoutDNN. Furthermore, based on this configuration, the UE_ 10 may transmitthe PDU session establishment request message without DNN.

As described above, the UE_A 10 may perform similar processingregardless of whether the first type of congestion control is tor aspecific DNN or for No DNN.

That is, upon a PLMN change, in a case that the UE_A 10 has the back-offtimer for the first type of congestion control associated with theunchanged PLMN running, or the back-off timer for the first type ofcongestion control associated with the unchanged PLMN is deactivated,and in a case that the back-off timer for the first type of congestioncontrol associated with the PLMN resulting from the change is notrunning, or the back-off timer for the first type of congestion controlassociated with the PLMN is not deactivated, then the UE_A 10 isconfigured to be able to transmit, in the new PLMN, the PDU sessionestablishment request message with the specific DNN, restricted by thecongestion control associated with the unchanged PLMN, and/or the PDUsession establishment request message without DNN.

Alternatively, the UE_A 10 may perform different processing depending onwhether the first type of congestion control is for a specific DNN orfor No DNN.

Upon a PLMN change, in a ease that the UE_A 10 has the back-off timerassociated with the first type of congestion control for a specific DNNrunning, or the back-off timer associated with the first type ofcongestion control for the specific DNN is deactivated, then the UE_A 10is configured not to perform, in the new PLMN, transmission of the PDUsession establishment request message using the specific DNN.Accordingly, based on this configuration, the UE_ 10 may be restrictedfrom transmitting the PDU session establishment request message with thespecific DNN.

Here, the UE_A 10 does not stop the back-off timer being counted by theUE_A 10 and may continue counting until the timer expires.Alternatively, the UE_A 10 may continue to hold the deactivated back-offtimer in a deactivated state.

Thus, the first type of congestion control for a specific DNN may alsobe applied in a different PLMN.

On the other hand, upon a PLMN change, in a case that the UE_A 10 hasthe back-off timer associated with the firs(type of congestion controlfor No DNN running, or the back-off timer associated with the first typeof congestion control for No DNN is deactivated, the UE_A 10 isconfigured to be able to transmit, in the new PLMN, the PDU sessionestablishment request message without DNN. Accordingly, based on thisconfiguration, the UE_10 may transmit the PDU session establishmentrequest message with the specific DNN.

Here, the UE_A 10 does not stop the back-off timer being counted by theUE_A 10 and may continue counting until the timer expires.Alternatively, the UE_A 10 may continue to hold the deactivated back-offtimer in a deactivated state.

As described above, the first type of congestion control for No DNN maybe associated with the PLMN.

For example, in a case that the first type of congestion control for NoDNN is applied, the UE initiates counting with the back-off timerassociated with the PLMN and No DNN. In a case that the back-off timeris not zero or deactivated, the UE does not perform, in the PLMNassociated with the back-off timer, establishment of a PDU session usingNo DNN associated with the back-off timer. Additionally, in a case thatthe back-off timer is deactivated, the UE does not perform, in the PLMNassociated with the back-off timer, establishment of a PDU session usingNo DNN associated with the back-off timer until the terminal is poweredoff or the USIM is removed. Additionally, in a case that the back-offtimer is zero, establishment of a PDU session using No DNN associatedwith the back-off timer may be performed in the PLMN associated with theback-off timer.

In other words, upon a PLMN change, in a case that the UE_A 10 has theback-off timer for the first type of congestion control for No DNNassociated with old PLMN running, or the back-off timer for the firsttype of congestion control for No DNN associated with the old PLMN isdeactivated, and in a case that the back-off timer for the first type ofcongestion control for No DNN associated with new PLMN is not running,or the back-off timer for the first type of congestion control for NoDNN associated with the PLMN is not deactivated, then the UE_A 10 isconfigured to be able to transmit, in the new PLMN, the PDU sessionestablishment request message without DNN. Furthermore, based on thisconfiguration, the UE_ 10 may transmit the PDU session establishmentrequest message without DNN.

Here, as processing associated with a change of the PLMN describedabove, whether similar processing is to be performed regardless ofwhether the first type of congestion control is for a specific DNN orfor No DNN or different processing is to be performed may be configuredin advance based on information configured in the UE_A 10, but may bedetermined depending on whether a second PLAIN resulting from the changeis a PLMN equivalent to the first PLMN unchanged or not. For example, ina case that the second PLMN resulting from the change is not a PLMNequivalent to the first PLMN unchanged, similar processing may beapplied. Additionally, in a case that the second PLMN resulting from thechange is a PLMN equivalent to the first PLMN unchanged, differentprocessing may be performed.

Note that in the present embodiment, the expression “back-off timer isdeactivated” may be equivalent to the expression “back-off timer and/orthe congestion control associated with the back-off timer transitions toa deactivated state.” Note that, in a case of receiving a timer valueindicating deactivation, the UE_A 10 may deactivate the back-off timerand/or the congestion control associated with the back-off timer.

Here, the back-off timer to be deactivated and/or the congestion controlassociated with the back-off timer to be deactivated may be associatedwith one to four types of congestion control. Which type of congestioncontrol is associated with the back-off timer to be deactivated and/orthe congestion control associated with the back-off timer to bedeactivated may be similarly determined and recognized in a case thatthe back-off timer value is received.

More specifically, the UE_A 10 may receive, from the NW, the 14th and15th pieces of identification information indicating that the back-offtimer and/or the congestion control associated with the back-off timeris to be deactivated, and deactivate the back-off timer corresponding tothe type of congestion control indicated by the 15th piece ofidentification information.

Additionally, with the back-off timer and/or congestion controldeactivated, the application of the congestion control may continueuntil the terminal is powered off or the USIM is removed. Furthermore,the processing restricted at this time may be similar to the processingrestricted in a case that the back-off timer is counted in accordancewith the type of the congestion control.

Although the above description of the processing by the UE_A 10 and NWinvolved upon a PLMN change is directed to the first type of congestioncontrol and/or the back-off timer for the first type of congestioncontrol, similar processing may be performed for the second, third, andthe fourth types of congestion control. However, the PDU sessionestablishment request message for which the transmission is restrictedor accepted may be a message corresponding to each type. In other words,the congestion control and/or the back-off timer associated with thecongestion control may be associated with the PLAIN regardless of thetype of congestion control.

Alternatively, the configuration may be such that any type of congestioncontrol and/or the back-off timer associated with the congestion controlis associated with the PLMN. Thus, the first, second, and third types ofcongestion control may be configured such that the congestion controland/or the back-off timer associated with congestion control arcassociated with the PLMN. Alternatively, the first, second, and thirdtypes of congestion control for No DNN may be configured such that thecongestion control and/or the back-off timer associated with congestioncontrol is associated with a PLMN, and the first type of congestioncontrol for a specific DNN need not be associated with the PLMN. Notethat processing performed in a case that each type of congestion controlis associated with the PLMN and/or processing related to the back-offtimer corresponding to each type of congestion control may correspond tothe description of the processing for the first type of congestioncontrol associated with the PLMN and/or the processing related to theback-off timer corresponding to the first type of congestion controlassociated with the PLMN in which the first type of congestion controlis replaced with the second to fourth types of congestion control.Additionally, processing performed in a case that each type ofcongestion control is not associated with the PLMN and/or processingrelated to the back-off timer corresponding to each type of congestioncontrol may correspond to the above description of the processing forthe first type of congestion control not associated with the PLMN and/orthe processing related to the back-off timer corresponding to the firsttype of congestion control not associated with the PLMN in which thefirst type of congestion control is replaced with each of the second tofourth types of congestion control. However, as described above, the PDUsession establishment request message for which the transmission isrestricted or accepted may be a message corresponding to each type.

Additionally, in the description of the present embodiment, theexpression “NW transmits to the UE_A 10,” may mean that the AMF or theSMF transmits to the UE_A 10, and the expression “UE_A 10 transmits tothe NW,” may mean that the UE_A 10 transmits to the AMF or the SMP.Furthermore, the expression “NW receives from the UE_A 10” may mean thatthe AMF or the SMF receives from the UE_A 10, and the expression “UE_A10 receives from the NW” may mean that the UE_A 10 receives from the AMPor the SMF.

2. MODIFIED EXAMPLES

A program running on an apparatus according to the present invention mayserve as a program that controls a Central Processing Unit (CPU) and thelike to cause a computer to operate in such a manner as to realize thefunctions of the above-described embodiment according to the presentinvention. Programs or information handled by the programs aretemporarily stored in a volatile memory such as a Random Access Memory(RAM), a non-volatile memory such as a flash memory, a Hard Disk Drive(HDD), or another storage device system.

Note that a program for realizing such functions of the embodimentaccording to the present invention may be recorded on acomputer-readable recording medium. This configuration may be realizedby causing a computer system to read the program recorded on therecording medium for execution. It is assumed that the “computer system”refers to a computer system built into the apparatuses, and the computersystem includes an operating system and hardware components such as aperipheral device. Furthermore, the “computer-readable recording medium”may be any of a semiconductor recording medium, an optical recordingmedium, a magnetic recording medium, a medium dynamically retaining theprogram for a short time, or any other computer readable recordingmedium.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiment may be implemented orperformed on an electric circuit, for example, an integrated circuit ormultiple integrated circuits. An electric circuit designed to performthe functions described in the present specification may include ageneral-purpose processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor, or maybe a processor of a known type, a controller, a micro-controller, or astate machine instead. The above-mentioned electric circuit may includea digital circuit, or may include an analog circuit. Furthermore, in acase that a circuit integration technology that replaces the presentintegrated circuit appears with advances in semiconductor technology,one or more aspects of the present invention can also use a newintegrated circuit based on the technology.

Note that the invention of the present patent application is not limitedto the above-described embodiments. In the embodiment, apparatuses havebeen described as an example, but the invention of the presentapplication is not limited to these apparatuses, and is applicable to aterminal apparatus or a communication apparatus of a fixed-type or astationary-type electronic apparatus installed indoors or outdoors, forexample, an AV apparatus, a kitchen apparatus, a cleaning or washingmachine, an air-conditioning apparatus, office equipment, a vendingmachine, and other household apparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Various modifications are possible within thescope of the present invention defined by claims, and embodiments thatare made by suitably combining technical means disclosed according tothe different embodiments are also included in the technical scope ofthe present invention. Furthermore, a configuration in which constituentelements, described in the respective embodiments and having mutuallythe same effects, are substituted for one another is also included inthe technical scope of the present invention.

REFERENCE SIGNS LIST

-   1 Mobile communication system-   5 DN_A-   6 PDN_A-   10 UE_A-   20 UTRAN_A-   22 NB_A-   24 RNC_A-   30 PGW_A-   35 SGW_A-   40 MME_A-   45 eNB_A-   50 HSS_A-   80 E-UTRAN_A-   90 Core network_A-   120 NG-RAN_A-   122 NR node_A-   190 Core network_B-   230 SMF_A-   235 UPF_A-   239 UPF_C-   240 AMF_A

1. A User Equipment (UE) comprising: transmission circuitry, whereinupon Public Land Mobile Network (PLMN) change, in a case that firsttimer is deactivated for a Data Network Name (DNN) and old PLMN, butsecond timer is not running and is not deactivated for the DNN and newPLMN, the transmission circuitry is able to send a PDU SESSIONESTABLISHMENT REQUEST message for the DNN or no DNN in the new PLMNwithout stopping the first timer.
 2. The UE according to claim 1,wherein the first timer and the second timer are timers for DNN basedcongestion control.
 3. A communication control method performed by aUser Equipment (UE), the communication control method comprising: uponPublic Land Mobile Network (PLMN) change, in a case that first timer isdeactivated for a Data Network Name (DNN) and old PLMN, but second timeris not running and is not deactivated for the DNN and new PLMN, sendinga PDU SESSION ESTABLISHMENT REQUEST message for the DNN or no DNN in thenew PLMN without stopping the first timer.
 4. The communication controlmethod according to claim 3, wherein the first timer and the secondtimer are timers for DNN based congestion control.